On Friday, Apple (AAPL) is launching a second-generation iPhone, called the iPhone 3G, which addresses both of those problems, while retaining the look and feel of the first model’s hardware and software.

The base version of the new iPhone costs $199 — half the $399 price of its predecessor; the higher-capacity version is now $299, down from $499. Yet, this new iPhone is much, much faster at fetching data over cellphone networks because it uses a speedy cellular technology called 3G. And it now sports a GPS chip for better location sensing.

The company also is rolling out the second generation of its iPhone operating system, with some nice new features, including wireless synchronization with corporate email, calendars and address books. And there’s a new online store for third-party iPhone programs that Apple hopes will make the device usable for a wider variety of tasks, including gaming and productivity applications. This new software and store will also be available on older iPhones, through a free upgrade.

I’ve been testing the iPhone 3G for a couple of weeks, and have found that it mostly keeps its promises. In particular, I found that doing email and surfing the Internet typically was between three and five times as fast using AT&T’s 3G network as it was with the older AT&T network to which the first iPhone was limited.

Apple’s new iPhone operating system includes an ‘App store,’ where you can browse for, and download, third-party software.

The iPhone 3G is hardly the first phone to run on 3G networks, and it still costs more than some of its competitors. But overall, I found it to be a more capable version of an already excellent device. And now that it’s open to third-party programs, the iPhone has a chance to become a true computing platform with wide versatility.

There are two big hidden costs to the new iPhone’s faster speed and lower price tag. First, in my tests, the iPhone 3G’s battery was drained much more quickly in a typical day of use than the battery on the original iPhone, due to the higher power demands of 3G networks. This is an especially significant problem because, unlike most other smart phones, the iPhone has a sealed battery that can’t be replaced with a spare.

Second, Apple’s exclusive carrier in the U.S., AT&T Inc. (T), has effectively negated the iPhone’s up-front price cut by jacking up its monthly fee for unlimited data use by $10. Over the course of the two-year contract you must sign to get the lower hardware prices, that adds $240, overwhelming the $200 savings on the phone itself. If you want text messaging, the cost rises further. With the first iPhone, 200 text messages a month came free. Now, 200 messages will cost $5 a month, or another $120 over the two-year contract.

The iPhone 3G still has a couple of features that made the first version unpalatable to some potential buyers. It uses a virtual on-screen keyboard instead of a physical one. While I find the virtual keyboard easy and accurate, not everyone does. Also, in the U.S. and in many other countries, the iPhone is still tied to a single exclusive carrier, whose coverage or rate plans may be unacceptable to some.

Here is a rundown of the changes in the new model.

Design: The new iPhone looks almost exactly like the old one. It is the same length and width, has the same big, vivid screen, and has the same number and layout of buttons. The main difference is the back, which is now plastic instead of mostly metal and curved instead of flat. It’s very slightly thicker in the middle, with tapered edges, and weighs a tiny bit less.

The new iPhone 3G (left) delivers much higher Internet download speeds over cellular networks than the original iPhone (right).

Like its predecessor, the iPhone 3G comes in two models distinguished only by storage capacity: 8 gigabytes and 16 gigabytes. The top model is available in black or white.

Apple has greatly improved the audio on the new iPhone. I found the speaker was much louder, for music and for the speakerphone. But the new phone produced an echo when used with the built-in Bluetooth system in my car. Also, the headphone jack is now flush with the case instead of recessed as on the first model, so it can accept any standard stereo earphones.

The camera, however, is still bare-bones. It can’t record video and has a resolution of just two megapixels. The power adapter is now tiny, at least in the U.S., but Apple no longer includes a dock for charging, just a cable.

Software: The basic software is similar. The biggest addition for some users will be full compatibility with Microsoft’s (MSFT) widely used Exchange ActiveSync service, which many corporations use. In my tests, I was able to connect the iPhone 3G to my company’s Exchange servers in a few minutes, and my corporate email, calendar and contacts were replicated on the phone. Any changes I made on the iPhone were reflected almost instantly in Microsoft Outlook on my company PC, and vice versa. Email was pushed to the phone as soon as it was received on the company’s servers.

One drawback: While you can have both personal and Exchange email accounts on the new iPhone, if you synchronize with Exchange calendars and contacts, your personal calendar and contacts are erased.

The new iPhone and upgraded older iPhones also will be able to use a new Apple consumer service, MobileMe, which offers synchronized push email, calendars, photos and contacts.

There are other improvements. You can now delete multiple emails at once, set parental controls and search your contacts. You can also save photos in emails or from Web sites. You can also now open Microsoft PowerPoint files sent as attachments, though I found in my tests that opening larger PowerPoint files crashed the phone.

Some software features missing from the first iPhone are still AWOL on the new one. There’s no copy and paste function, no universal search, no instant messaging and no MMS for sending photos quickly between phones.

Network: Like the old iPhone, the new one can perform Internet tasks using either Wi-Fi wireless networking or the cellphone networks. But the addition of 3G cellular capability makes the new model more useful for Web surfing, email and other data tasks when you’re not in Wi-Fi range. In my tests, in Washington and New York, I got data speeds mostly ranging between 200 and 500 kilobits per second. By comparison, the original iPhone, tested in the same spots at the same time, mostly got cellular data speeds between 70 and 150 kbps on AT&T’s old EDGE network. The new iPhone typically was between three and five times as fast as the old one.

While AT&T now has 3G networks in 280 U.S. cities, and aims to be in 350 by year end, it is converting its cellphone towers gradually, so not all areas of included cities have 3G coverage. The new iPhone falls back to EDGE speeds when 3G isn’t present.

One side benefit to 3G is that in some areas, voice coverage improves. At my neighborhood shopping center, where the first iPhone got little or no AT&T service, the iPhone 3G registered strong coverage. But I still found that calls regularly broke up on some major streets. In New York City, riding in a taxi along the Hudson, one important call was dropped three times on the new iPhone. Finally, I borrowed a cheap Verizon (VZ) phone and got perfect reception.

Battery life: Apple claims that over 3G, the new iPhone can get five hours of talk time, or five hours of Internet use. Talk time is twice as long on the older EDGE network, and Internet time is an hour better with Wi-Fi.

I ran my own battery tests using the phone’s 3G capability. Although I left the Wi-Fi function on, I didn’t connect it to a network, so the phone had to rely on 3G. In my test of voice calling, I got 4 hours and 27 minutes, short of Apple’s maximum claim and nearly three hours less than what I recorded in the same test last year on the original iPhone. In my test of Internet use over 3G, I got 5 hours and 49 minutes, better than Apple’s claim, but far short of the nine hours I got using Wi-Fi in last year’s tests.

More important, in daily use, I found the battery indicator on the new 3G model slipping below 20% by early afternoon or midafternoon on some days, and it entirely ran out of juice on one day. I overcame this problem by learning to use Wi-Fi instead of 3G whenever possible, turning down the screen brightness and even turning off 3G altogether, which the phone permits.

The iPhone 3G’s battery life is comparable to, or better than, that of some other 3G competitors. But they have replaceable batteries. The iPhone doesn’t.

Third-party software: If things go as Apple hopes, third-party software could be the biggest attraction to the new iPhone 3G, and to upgraded older iPhones. By some estimates, there will be hundreds of these programs, some free and some paid, almost immediately.

Apple didn’t supply me with programs for testing, but I managed to try several on older devices upgraded to the new operating system. I tested a game that used the phone’s motion sensors to control the action, and I tested several programs from America Online (TWX), including AOL Instant Messenger; AOL Radio, which streams music from the Internet; and AOL’s Truveo video search engine. All worked very well.

Among the programs Apple has publicly previewed were a sales automation program from Salesforce.com, a game called Super Monkey Ball from Sega and a program for bidding on eBay (EBAY). Also made public were a news reader from the Associated Press, a program for following live games from Major League Baseball and several programs for doctors, including the Epocrates drug reference.

Bottom line: If you’ve been waiting to buy an iPhone until it dropped in price, or ran on faster cell networks, you might want to take the plunge, if you can live with the higher service costs and the weaker battery life. The same goes for those with existing iPhones who love the device but crave faster cellular data speeds. But if you already own an iPhone, and can usually use Wi-Fi for data, you probably should hold off and get the free software upgrade before deciding whether it’s worth getting the new hardware.

Find all of Walt Mossberg’s columns and videos online, free, at the All Things Digital Web site, walt.allthingsd.com. Email him at mossberg@wsj.com.

Wireless cellphone earpieces can make people look faintly ridiculous as they stroll down the street or around the office, seemingly talking to themselves with ugly appendages sprouting from their heads. The pulsing blue lights on these things can make people look like robots. And these battery-powered gadgets, which use a power-hungry wireless technology called Bluetooth, are just one more thing to charge.

But such headsets are becoming more necessary, at least in the car. A growing number of cities and states are requiring all calls made while driving be conducted in a “hands-free” manner. Two more big states, California and Washington, will begin enforcing such laws in July. Unless drivers in these places have cars with costly built-in Bluetooth speakers and microphones, many will turn to wireless earpieces to make calls legally.

Now, two of the most important wireless earpiece makers are bringing out new models that attempt to make their products more attractive and functional. One is a new version of the Jawbone, which has become a leader in the high-priced end of the market. The other is a new model from Plantronics (PLT), which vies with Motorola (MOT) as the top seller of wireless earpieces.

I’ve been testing both the new $130 Jawbone, and the $150 Plantronics Discovery 925, and both work well, despite some drawbacks. Each worked properly with both an inexpensive Motorola Razr phone from Verizon (VZ) and a sophisticated Apple (AAPL) iPhone from AT&T (T). But I preferred the Jawbone, because of its technology and design.

The new Jawbone, made by a closely held San Francisco company called Aliph, is 50% smaller than the original Jawbone, which I reviewed in 2006. It continues to boast the original Jawbone’s signature feature: a remarkable ability to suppress background noise and isolate the wearer’s voice.

Jawbone performs this feat by using a sensor that touches your skin lightly to identify your voice through the vibration of the bones in your face. Using this information, its microphone can more easily distinguish your voice from background noise, and accurately suppress the latter.

This feature, originally called “Noise Shield” and now theatrically renamed “Noise Assassin,” really works. When the company first showed off the original Jawbone, it made live calls standing in front of things like weed whackers and boom boxes, and then turned the bone-sensing feature on and off to show the dramatic difference.

Aliph’s new Jawbone

In my tests of the new, much smaller Jawbone, I stood a few feet from a roaring vacuum cleaner, while on a phone call. The person I was calling could barely hear me with Noise Assassin turned off, but could clearly make me out when I turned it on.

By contrast, the Plantronics Discovery failed my noise test. It was useless anywhere near the vacuum cleaner. This was obviously an extreme case, but it served as a stand-in for other loud noises likely to be encountered in real life, like large trucks, or construction gear on the streets.

The biggest flaw in the original Jawbone, in my 2006 tests, was its performance in wind, which was poor. The Jawbone did much better in my latest tests. During a Jawbone call from a car with all the windows down and the sunroof open, my voice was easy to make out, according to the person I was calling. The new Plantronics earpiece did just as well in this wind test.

Plantronics claims its headset also enhances the voice of the person you are calling, a claim Aliph doesn’t make for the Jawbone. But, while voices sounded fine on the Plantronics, I couldn’t detect any difference between the two on that score.

Both gadgets are meant to be more stylish, and both will be available in multiple colors. But, while the Jawbone is just a smaller iteration of its original slab-like form, Plantronics has done something more radical with the Discovery 925: It has tried to make it look like jewelry. The Discovery’s electronics are housed in the diamond-shaped portion of the device that goes on the ear, and the microphone sits at the end of a long, V-shaped boom that is open in the center. Plantronics says the design is suitable for both genders, but admits it is a bit more aimed at women and at fashion-conscious men.

I believe some men wouldn’t feel comfortable wearing this new Plantronics model. It’s also longer than the Jawbone. But I did find it more comfortable to wear, since it doesn’t protrude as much into the ear.

The Plantronics claims longer talk time — five hours vs. four hours for the Jawbone, but the Jawbone claims longer standby time — eight days, vs. seven days for the Plantronics. The Jawbone weighs more, at 10 grams, compared with 8 grams for the Plantronics, but neither felt heavy on my ear.

I did prefer the Plantronics’ controls over the Jawbone’s. The former uses obvious buttons, while the latter employs unmarked, hidden buttons whose location you have to learn by touch.

Both of these earpieces do the job, but if you have to choose one, I’d pick the Jawbone.

• Find all of Walt Mossberg’s columns and videos online, free, at the All Things Digital Web site, walt.allthingsd.com. Email him at mossberg@wsj.com.

Corrections & Amplifications:

The Aliph Jawbone cellphone earpiece weighs 10 grams, and the Plantronics Discovery 925 earpiece weighs 8 grams. An earlier version of this column erroneously reported the products’ weights in ounces.

But what if you only have a standard cellphone with a lousy Web browser — or even the best Web-browsing phone, but it lacks a fast data connection? What if you’re speeding down the road in a car, where typing is dangerous?

Now, there’s a way to get your questions answered despite those hurdles. It’s a free cellphone service that lets you ask any question answerable via a Web search, using any cellphone, by simply making a voice call. It’s called ChaCha, and I’ve been testing it out.

To use ChaCha, you just dial 800-2chacha (800-224-2242) and state your question. In a few minutes, you’ll get an answer via text message. In one test, I asked ChaCha who was the winning pitcher in the previous night’s Red Sox victory against the Yankees. In a few minutes, I received a text message with the correct answer: Daisuke Matsuzaka.

ChaCha requires no registration and works on any cellphone carrier. It needs no special codes or key words. You just state your question as if you were asking a friend. If you prefer to type your question, you can text it to “ChaCha,” or 242242. Though ChaCha itself charges no fees, your phone carrier may charge for the minutes you use, or for the text messages.

The service works by routing your questions to one of 10,000 hired “guides” — students, stay-at-home parents, retirees and others — who look up the questions on the Web and reply. They get paid 20 cents per answer.

Naturally, these guides vary as to their speed and accuracy. If you don’t like the answers they give you, or you want related information, you can call back or reply to the text message with a follow-up question. For instance, after learning which pitcher had won for Boston, I asked who lost the game for New York. I was quickly informed it was Phil Hughes.

Overall, I liked ChaCha. In most cases, I received fast, accurate, useful answers. But it has two weaknesses. One is that the low-paid, part-time guides can provide inconsistent service. When I asked for the best Mexican restaurant in D.C., for example, ChaCha came up with a choice that few locals would cite.

The other is that, unlike many other cellphone information services, ChaCha doesn’t automatically know your location. So, unless you include a location in your query, it’s clueless about questions such as “Where’s the nearest drugstore?”

ChaCha is hardly the only information service for cellphones. Google offers a text-message service where you can ask questions on a wide variety of topics, and a voice-based service that locates businesses near your location. Microsoft’s TellMe subsidiary just introduced a voice-based service that answers location-specific questions about businesses, weather, traffic and movies, and displays the answers on the screens of BlackBerrys.

But these competitors are more limited than ChaCha in key respects. Google’s broader mobile-search service, Google SMS, requires that questions be sent via text message using special key words. Its voice service, Goog411, finds only local businesses. TellMe’s new service is limited to location-based information and works only on certain phones.

I tested ChaCha using three very different phones: a cheap, bare-bones Samsung flip phone from Sprint; a midrange Motorola Razr from Verizon; and an Apple iPhone running on AT&T. I asked questions via voice and text from various locations, including my car, where I used a hands-free microphone.

I asked about sports, TV shows, journalism, history, weather, nutrition, demographics and shopping. ChaCha handled most of these inquiries correctly and was able to fix most of its errors after I asked follow-up questions. For each question, it sends two text messages: one restating your query and saying it’s working on it, and the second containing the answer.

Each ChaCha answer is accompanied by a Web link. If your phone has a decent browser, you can go to that link to learn who the guide was, and what his or her Web-site source was.

ChaCha gave me the weekend weather forecast in Boston, the date of death of Abigail Adams and the cast of the TV show “Brothers & Sisters.” It provided Peyton Manning’s salary and the sodium content of a McDonald’s quarter pounder. Its most impressive performance came when it correctly answered an obscure historical question: “When was the Gaspee burned?” The Gaspee was a British tax-collection ship burned in Rhode Island in 1772 in what is often considered the first act of war of the American Revolution.

The company is working on adding automated location knowledge, at least on certain carriers and phones. For now, you can tell it your location by sending a special command via text message. But even without the location features, ChaCha is a fun and useful service.

Find all of Walt Mossberg’s columns and videos online, free, at the new All Things Digital Web site, http://walt.allthingsd.com. Email him at mossberg@wsj.com.

Corrections & Amplifications

ChaCha, a mobile-phone search service, is incompatible with several small U.S. cellphone carriers. This column incorrectly said that the service works on any cellphone carrier, based on incorrect information supplied by the company.

That may sound like Apple’s heavily publicized iPhone, which runs on the AT&T wireless network, but it’s not. This phone is called the Voyager, and it’s made by LG and runs on the rival Verizon Wireless network.

Despite their superficial similarities, the two devices are very, very different. In fact, Verizon’s public-relations people are at pains to say the Voyager isn’t intended as an “iPhone killer” or even a “smart phone.”

Still, the Voyager is worth a close look, if only because it is one of the first competitors that attempts to mimic Apple’s touch interface, and many of its functions overlap the iPhone’s.

The Voyager beats the iPhone in certain respects. Unlike Apple’s product, it runs on a fast, 3G data network. And my experience has been that Verizon’s network has better coverage than AT&T’s in many cities, especially on the East Coast. It also costs less: $299, after a rebate, with a two-year service contract, compared with $399 for the iPhone.

In addition, the Voyager has GPS and thus provides real-time navigation, a capability the iPhone currently lacks. And the Voyager can even receive live TV programs for an extra monthly fee of $15, though it gets only eight channels and its TV function works only in certain cities.

A big advantage of the Voyager for some people is that it has a physical keyboard for typing in addition to the kind of virtual onscreen keys that are the iPhone’s only method for entering text. This keyboard is revealed by opening the phone, which then resembles a little laptop with a display that’s separate from the outside touch screen. I found that typing worked pretty well. For folks who insist on a physical keyboard, this is a big deal.

Finally, LG has enhanced the Voyager’s touch screen with feedback: When you tap an icon or scroll through a list, you get a light physical sensation.

But the Voyager is bulkier than the sleek iPhone — about 50% thicker and 40% larger overall — even though it’s a tad lighter. And it lacks the iPhone’s ability to use Wi-Fi hot spots and home networks, which are often faster than Verizon’s 3G network. It also has only about half the battery life; a smaller, lower-resolution screen, and just a fraction of the Apple’s internal memory. (Unlike the iPhone, the Voyager lets you add memory cards, but it doesn’t come with any.)

Most importantly, the Voyager suffers badly in the area where Apple’s phone shines: software. Whether Verizon considers it a direct iPhone competitor or not, the LG product tries to do many of the same things, and it generally falls short.

This is the true challenge that the iPhone poses to established phone makers like LG. Apple has managed to build into its phone a real PC-grade operating system with a breakthrough user interface and elegant programs, something that has eluded the major cellphone makers.

As with so many of the new feature-packed mobile phones, the Voyager’s user interface is clumsy and confusing, requiring too many steps to perform simple tasks. And its applications, such as the photo organizer, music player, Web browser and email program, are primitive compared with the iPhone’s.

In fact, the Voyager, bafflingly, has several different user interfaces — two on the outer touch screen and an entirely different one on the inner screen above the keyboard that doesn’t work by touch at all. Some functions work only with the inner screen.

Scrolling through lists with the Voyager’s touch screen is a halting, frustrating process compared with the smooth, slick scrolling on the iPhone. Its touch functions are old style and basic compared with the new “multitouch” approach that Apple built into the iPhone. Unlike the iPhone, the Voyager doesn’t allow you to “flick” through photos or other screens, or to use two fingers to enlarge or shrink photos or Web pages. It also doesn’t automatically change photos or Web pages from portrait to landscape view by just turning the phone.

In addition, while the Voyager’s Web browser can show real Web-page layouts, I found it to be far inferior to the iPhone’s browser, which shows entire pages and then zooms in on the parts you want to read with a couple of finger taps.

Apparently because the Voyager isn’t considered a business tool or smart phone, its email function isn’t included on any of the main menus or even located under the envelope icon labeled “messaging.” To find it, you have to wade through multiple menus with unhelpful names like “Tools on the Go.”

Even doing something as simple as entering flight mode — which turns off a phone’s internal radios for use on a plane and takes two steps on the iPhone — requires five steps on the Voyager.

Verizon is promising to improve the Voyager, but right now it’s a classic example of how the leading cellphone makers are going to have to step up their games, especially in software, to match Apple’s upstart device.

• Email me at mossberg@wsj.com. Find all my columns and videos online free at the new All Things Digital Web site, http://walt.allthingsd.com.

There are several reasons for this, including the security problems in the dominant Windows platform from Microsoft; spillover from Apple’s blistering success with its iPod music players; the fact that Macs can now run Windows programs; and Apple’s highly successful chain of company-owned retail stores.

But another key factor has been the Mac operating system, called OS X, which came out in 2001. It has proved to be as powerful and versatile for mainstream consumers as Windows, yet easier to use and more secure. And Apple has upgraded OS X far more rapidly than Microsoft Inc. has upgraded Windows, bringing out major new releases roughly every 18 months, while Microsoft struggled for more than five years to produce the latest Windows iteration, Vista, which came out in January.

On Friday evening, Apple will release yet another new version of OS X, called Leopard, to replace the current version, known as Tiger. I’ve been testing Leopard, and while it is an evolutionary, not a revolutionary, release, I believe it builds on Apple’s quality advantage over Windows. In my view, Leopard is better and faster than Vista, with a set of new features that make Macs even easier to use.

Leopard will come preinstalled on all new Macs. It can also be purchased for $129 as an upgrade to existing Macs that, depending on configuration, can be as many as six years old. Unlike Vista, which is sold in four noncorporate upgrade versions ranging from a $100 stripped-down “basic” edition to a $259 deluxe “ultimate” edition, there’s only one version of Leopard. It includes all the features, from those aimed at novices to those aimed at power users.

For me, the marquee features in Leopard are a new function called Time Machine that automatically backs up your entire computer in the background; two new methods, called Cover Flow and Quick Look, for rapidly viewing the contents of files without opening any programs; and new techniques that allow you to access the files in, and to remotely control, other computers on your network or connected over the Internet with a few clicks and no technical expertise.

Plus, Apple’s free software for running Windows on a Mac, called Boot Camp, which was formerly an add-on users had to download and install, is now built right into the operating system. And, in my tests, the third-party Fusion program for running Windows and Mac programs simultaneously continued to work fine in Leopard.

I did notice a few drawbacks, but they were minor. The menu bar is now translucent, which can make it hard to see the items it contains if your desktop picture has dark areas at the top. The new folder icons are dull and flat and less attractive than Vista’s or their predecessors on the Mac. While Time Machine can perform backups over a network, the backup destination can only be a hard disk connected to a Mac running Leopard. And, on the Web, I ran into one site where the fonts on part of the page were illegible, a problem Apple says is known and rare and that I expect it will fix.

While Apple claims the new system includes more than 300 new features, there is nothing on the list that could be considered startling or a major breakthrough. Some of Leopard’s features are unique, but many others — such as backing up data and quickly viewing files — have been available on both Windows and the Mac via third-party programs or hard-to-find geeky methods buried in the operating systems. Leopard has made them easy to find and use.

When I upgraded my personal iMac desktop to Leopard, it took less than an hour, and after the process was complete, all my programs, including the Mac version of Microsoft Office, the Firefox Web browser and Adobe Reader, worked rapidly and fine. I was still able to run Windows XP via Fusion. And my previous installation of Boot Camp, which turns the iMac into a speedy, full-fledged Vista machine after a reboot, worked perfectly. All my Vista programs and files continued to function properly.

With Cover Flow, users get a visual preview of a computer’s files without having to open programs.

In fact, every piece of software and hardware I tried on two Leopard-equipped Macs — a loaned laptop from Apple and my own upgraded iMac — worked fine, exhibiting none of the compatibility problems that continue to plague Vista. My old Hewlett-Packard inkjet printer, for which Vista lacks the proper software, worked instantly in Leopard, even over the network. And, unlike with Vista, it was able to print on both sides of the page. I popped my old Verizon cellphone modem card into the test Leopard laptop and it worked, too, with no software installation or tweaking.

Leopard felt about as fast as Tiger, and it started up much faster than Vista in my tests. I compared a MacBook Pro laptop with Leopard preinstalled to a Sony Vaio laptop with Vista preinstalled. Even though I had cleared out all of the useless trial software Sony had placed on the Vaio, it still started up painfully slowly compared with the Leopard laptop.

It took the Vista machine nearly two minutes to perform a cold start and be ready to run, including connecting to my wireless network. The Leopard laptop was up, running and connected to the network in 38 seconds. In a test of restarting the two laptops after they had been running an email program, a Web browser and a word processor, the Sony with Vista took three minutes and 29 seconds, while the Apple running Leopard took one minute and five seconds.

Here’s a rundown of some of Leopard’s key features. Much more detailed information is available at apple.com/macosx.

File management: Apple’s Finder, the equivalent of Explorer in Windows, now offers two new ways to quickly see what your files contain. You can still view them as icons or lists. But you can also use Cover Flow, the same system Apple uses in iTunes and on the iPhone to display album covers for music. In Leopard, a large preview of each file you select appears above the list of files in a folder, and you can rapidly scroll through these icons. These previews are live, and their contents can be viewed without opening the program that is normally needed to display them.

Time Machine backs up files.

For instance, if the file is a video, you can just click on it, and it will play. If it’s a multipage PDF file, you can click on it, and arrows will appear allowing you to flip through the pages.

An even better and deeper look can be obtained using a feature called Quick Look. Just hit the space bar or click on a toolbar icon, and a preview of any selected file zooms out. You can even view multiple sheets in an Excel file via Quick Look without launching Excel.

Another quick new way to see your files is available in the Dock, the Mac’s equivalent of the Windows Task Bar. Here, any folder you place on the right side of the dock will display its contents, after a single click, either as a grid of icons displaying miniversions of the file or as a “fan,” or arc, of such icons. These special Dock folders are called “Stacks.” Leopard includes one by default that is the destination for everything you download from the Internet, so your desktop will no longer get cluttered with downloads,

Time Machine: This built-in feature will continuously back up all of the contents of your Mac to either an external hard drive directly connected to the computer, or to a hard disk connected to another Mac running Leopard that’s on your network. The initial backup, in my tests, took all night, but after that, the system updates the backups hourly and I didn’t notice any slowdown during the process.

To recover any file you deleted, you simply click on the Time Machine icon, and you are taken to a view that shows file folders — or your email or address book or photo collection — in a stack of windows that appear to go on infinitely. You click on an arrow and the stack of windows zooms until you arrive at the last view in which the missing file existed. Then, you click “restore,” and the file is recovered in your normal desktop view. You can also restore whole folders, groups of files, or even an entire hard disk.

Shared computers: In Leopard, any computer that has been set to be shared on your network shows up on the left side of every Finder window. Click on it, and you can access whatever folders have been shared on those machines. Depending on the remote computer’s security settings, you may first have to enter a user name and password. It’s the simplest method I’ve ever seen for accessing other computers on a network. And it works with Windows PCs as well as Macs. When I first turned on the Leopard laptop in my office, it immediately found a shared folder on my colleague’s old Dell running Windows XP. She hadn’t even remembered sharing the folder, which contained files from 2003.

You can copy or move files to and from these shared computers, or view their contents with Cover Flow and Quick Look, or open them in programs on your own computer.

If you are a member of Apple’s optional .Mac service, which costs $100 a year, you can use a feature called “Back to My Mac,” which can access your Macs from thousands of miles away over the Internet. However, this feature works only over certain kinds of routers (not all of them Apple’s) and, as my router didn’t qualify, I couldn’t test it.

Remote control: For any Mac in your shared-computers list for which you have permission, you can take over the screen by simply clicking on a button called “Share Screen.” You can also remotely control distant Macs over the Internet using Apple’s built-in iChat instant messaging program, as long as you have permission and the Macs are running Leopard.

Stacks displays the files in folders in the dock.

iChat: Apple now allows you to use its instant messaging program with Google Talk as well as AOL’s AIM service, and you can set up a video chat in which you can present a slide show or display a document. You can also add special backgrounds that can make it look as though you’re someplace else, like Paris. In my tests, this even worked with someone on the other end using a Windows XP computer running the latest version of AIM.

Spaces: In order to cut down desktop clutter, Leopard lets you set up as many as 16 different desktops that can run simultaneously, with different programs open in each. You switch among these desktops by using keyboard commands or a menu.

For instance, you might have your iPhoto and iTunes running in one “space,” or desktop, your Web browser and email program in another, and Windows XP in another.

Leopard isn’t a must-have for current Mac owners, but it adds a lot of value. For new Mac buyers, it makes switching even more attractive.

Email me at mossberg@wsj.com. Find all my columns and videos online free at the new All Things Digital web site, http://walt.allthingsd.com.

The latest, and most unusual, of these music phones has just been announced by Sprint. It’s a Samsung model called the UpStage. The UpStage costs just $149, less than a third of the iPhone’s planned $499 price, and it will go on sale early next month.

Samsung has shown real creativity in solving the problem of cramming a decent music player and phone into one small gadget. The slim UpStage has been designed with two distinct faces. On one side, it has a phone keypad and a small screen, for making voice calls and tapping out text messages. But if you turn it over, you see a larger screen and navigation controls, mainly for playing music, but also for other tasks, such as viewing online data.

Sprint’s UpStage music cellphone by Samsung.

At the same time, Sprint is slashing the price of songs sold on its proprietary music service from an outrageous $2.49 each to just 99 cents. That isn’t quite as cheap as it seems, because you have to pay $15 a month for the privilege of buying the 99-cent songs. But it’s still a positive step for consumers.

I’ve been testing the UpStage and found that its two-sided design works pretty well. It’s a better music phone, in my opinion, than Verizon’s Chocolate model, built by Samsung’s Korean rival, LG.

But the UpStage has too many weaknesses and compromises for me to recommend it. It has lousy battery life, both as a phone and as a music player, a limitation Sprint and Samsung have tried to offset with a free add-on that makes the phone too bulky. And it comes with so little memory that, out of the box, it can hold only around 20 average songs. Adding more capability costs extra, thus lessening the price advantage. There are other downsides as well.

I tested the UpStage primarily as a music player, because that’s its claim to fame. I compared it with the base-model iPod Nano, which also costs $149, although of course it doesn’t include a phone.

I did try out the basic phone stuff, like making calls, all of which seemed OK, though the screen on the phone side of the device is very small, a sort of throwback to early cellphones. Sound quality, reception and the keypad all were fine. The built-in 1.3 megapixel camera is standard for phones these days.

Only one of the phone’s two screens can be used at any one time, and you have to press a “flip” button on the side to switch. This worked well, but was kind of a pain when I was trying to use the keypad to type in text, like a Web password or the name of a new song playlist, on the music side of the phone. I had to flip to the side with the keypad and then flip back.

I loaded in about 20 songs and the UpStage played them back pretty well, displaying all the correct song information and album art. I also loaded in some photos, which also displayed fine, though the phone can handle only small picture files. I purchased a song from Sprint’s music service, and that downloaded and played well.

The only problems were that the album covers and photos looked grainy, because even the larger screen has pretty low resolution. And occasionally, the start of a song was clipped. The iPod Nano exhibits neither of these problems.

Out of the box, the UpStage comes with only a tiny memory card, which can hold only around 20 standard MP3 files. The iPod Nano can hold 500 of those files. To get the same capacity on the UpStage, you have to buy a larger, $40 memory card.

Though the UpStage is bigger than the iPod Nano, it has far worse battery life — just 2.5 hours of talk time for the phone and seven hours of music playback time, compared with up to 24 hours of music playback time for the Nano. To compensate, Sprint is throwing in a “battery wallet,” a case with an additional battery built in. This brings the talk time to 6.3 hours and music playback time to around 17 hours. But it makes the phone twice as thick.

There are two other problems with the UpStage. First, synchronizing its music with songs stored on a PC requires you to install and use Sprint music software. It doesn’t work with Windows Media Player or the Windows version of Apple iTunes, which most music lovers already own. (You also can manually drag and drop songs onto the phone’s memory card.)

Second, the navigation pad on the music side of the phone can be confusing. It works by touch controls; you have to use just the right pressure and slide your finger just the right distance along its sides to get it to work right. It’s too complicated.

Samsung and Sprint deserve credit for a good try with the UpStage. But it doesn’t quite cut it.

Email me at mossberg@wsj.com. See video versions of my reviews at wsj.com/mossbergvideo.