Beginning this summer, as soon as next month, wireless Internet access will arrive in the passenger cabins of some commercial U.S. airliners.

On these Internet-equipped planes, any passenger with a Wi-Fi enabled laptop — or a cellphone with Wi-Fi — will be able to do almost everything he or she could do online at home or at the office. That includes surfing the Web, using email, having instant-messenger text chats, downloading and uploading files, and streaming video and audio.

In fact, I did all these things a few days ago on a test flight using the new system, called Gogo. During the flight from San Francisco to Denver, on a small test jet, I could operate online as if I were sitting at my desk, or in a Starbucks. I used Dell (DELL) and Apple (AAPL) laptops, a BlackBerry (RIMM), a Windows Mobile phone and an iPhone to perform all the most common online tasks, while soaring over majestic mountains and glorious national parks.

I sent and received emails on Microsoft (MSFT) Outlook and Apple Mail, including messages with hefty attachments. I conducted IM chats on AOL (TWX) Instant Messenger and Google (GOOG) Talk. Using all the major Web browsers, I called up dozens of Web sites, and watched video clips on Hulu and YouTube. I downloaded photos, songs, PDF files and Microsoft Office documents. I used all the Internet functions on the iPhone, and on the Wi-Fi-equipped BlackBerry and Windows Mobile phone.

One important caveat: Gogo is a data-only system. It doesn’t allow phone calls and will block all services that allow voice conversations to be made over the Internet.

Gogo will launch on three American Airlines (AMR) routes, likely in July. The first planes to use it will be American’s 15 Boeing 767s flying between New York and Los Angeles, San Francisco and Miami. Later in the year, Gogo will be available on all of Virgin America’s small number of routes, and possibly additional American routes, if the first deployment works well. It’s supplied to the airlines by a Denver-based company called Aircell, which says it is in negotiations to offer the Gogo service on several other major U.S. airlines by next year.

The Gogo service will cost a flat fee of $12.95 for flights of three hours or longer, and $9.95 for shorter trips. You log into Gogo as you would any commercial Internet service, registering on a special Web page. Aircell plans to allow advance sign-up, so you’d only have to enter an ID and password on the plane. No add-on software, hardware or cables are required.

A few Web functions will be offered free from Gogo, including access to the American Airlines Web site, to Frommer’s online travel guides and to a limited selection of articles from The Wall Street Journal.

Gogo isn’t the first in-plane Internet service. A few years ago, Lufthansa (LHA.MU) offered a satellite-based service from Boeing (BA), mainly on over-ocean flights, but it was canceled.

The service operates at respectable, if not blazing, speeds — similar to what you’d get on a cellular broadband service or a slow home DSL line. On my test flight, download speeds varied from 266 kilobits per second to about 1.4 megabits per second, with the most typical speeds hovering between 500 and 600 kbps. Upload speeds were between 250 and 300 kbps. I found that most of the tasks I tested, except for streaming video, felt smooth and normal.

Speeds could degrade on a large plane with scores of people online simultaneously. But Aircell claims it has the technology to make my experience representative for anyone doing common tasks, such as Web surfing and email. During my test flight, eight laptops and six Wi-Fi-enabled smart phones were using the system simultaneously. All registered decent speeds, except for a couple of minutes when the plane was crossing between the zones controlled by the company’s ground-based towers.

Aircell gets Internet access to the planes through a network of 92 towers scattered across North America. These essentially are cellphone towers, carrying a high-speed cellphone data signal, except that the Aircell antennas point up, into the sky. A receiver on the underside of the aircraft picks up the signal, which is then distributed through the plane via Wi-Fi.

The companies say Gogo is safe and won’t interfere with the plane’s operation. It is government-approved, and pilots can shut the system off should they deem it necessary.

Gogo has some limitations. The service plans to allocate its capacity so that low-bandwidth activities like Web surfing and email take priority over high-bandwidth ones like streaming video. That means you may find video to be slow and halting.

And Gogo is a North American, land-based service only. It won’t work over the oceans and, for now, it won’t work on other continents.

But for U.S. travelers who want to stay connected in the air, Gogo does the job.

• 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.

Hard-disk drives, or HDDs, are mechanical devices. They work by recording data on a spinning magnetic platter or platters. By contrast, solid-state drives are made of chips and have no moving parts. They are close cousins to the so-called flash memory used in digital cameras, cellphones and smaller-capacity music players. They record data to special memory chips that retain their contents even when the device is turned off.

Solid-state drives have some key advantages. Because they lack moving parts, they are faster, draw less power, are harder to damage and are quieter than hard drives. Unfortunately, today’s early versions of SSDs for laptops also have two big drawbacks when compared with hard drives: They offer much lower capacity and have much higher prices.

For instance, on the newly announced Apple MacBook Air ultrathin laptop, the HDD version costs $1,799 and stores 80 gigabytes. The SSD version costs $2,798, but actually stores less — just 64 gigabytes. On the Toshiba Portege R500 subnotebook, the basic hard-drive version costs $1,999 and stores 120 gigabytes. The cheapest SSD version is $2,699 and also stores just 64 gigabytes.

Despite these limitations, I believe SSDs are likely to become more common and more popular as their capacities increase and their prices drop. Samsung, which makes the 64-gigabyte SSDs in both the Apple and the Toshiba, has already announced an SSD with twice the capacity that costs much less per gigabyte of storage.

I’ve been testing the SSD models of the Portege R500 and the MacBook Air to see how they measure up to their HDD counterparts. My verdict is that the SSD does deliver on its promises, but, in some cases, just barely.

For the small slice of users who are deeply and constantly worried about hard-disk failures, it may be worth it to pay a huge premium today for an SSD that stores less. Because SSDs aren’t subject to mechanical failures, your data are probably safer on them. But for mainstream users, my conclusion is that it’s too early to take the plunge on SSDs, and the best strategy is to wait for prices to drop sharply and for capacity to rise.

In my tests, I focused solely on comparing the hard-drive and SSD models of each machine, which I had had already reviewed in earlier columns. On the same computer, I wondered, would the SSD make a significant difference in speed and in battery life?

To measure battery life, I conducted my usual harsh test, where I turn off all power-saving software, set screen brightness to maximum, turn on the Wi-Fi and play an endless loop of music.

In this test, the SSD made little difference in the MacBook Air and, in fairness, Apple is making no claims of any significant battery-life gains on its SSD model. The SSD MacBook gave me just five more minutes of battery life. Apple says this is because its hard-drive model already uses a very low-power drive.

On the Portege R500, my first battery test with the SSD model actually yielded significantly less battery life than the hard-drive model. The reason: Toshiba ships the base SSD model with a battery with only half of the capacity of the hard-drive model.

When I swapped in the normal battery, which costs $117 extra, the SSD model gave me an added 1 hour and 21 minutes of battery life, about a 36% increase. That extra battery life likely would translate to nearly 2½ hours in more normal usage. It may be worth the huge price premium for some folks.

On both computers, the SSD was faster than the HDD models. The SSD version of the Apple booted up from a cold start, and rebooted with several programs running, about 40% faster. But the gain isn’t as impressive as it seems because even the hard-drive versions of the MacBook Air booted up in under a minute and rebooted in just a little over a minute.

On the Toshiba, which was running Windows XP, the SSD model knocked about 40 seconds off a cold boot time on the HDD version of 2 minutes and 7 seconds. On my reboot test, starting with several programs running, the SSD model was 80 seconds faster. I imagine that on laptops with the slow-booting Windows Vista, the improvements might be more meaningful.

I also tested launching Microsoft Word and Excel, and opening a couple of hefty PDF files on both machines. The SSD versions were faster. But in most cases, the gains were just a few seconds or even fractions of a second.

All in all, the SSD is a promising improvement over the hard drive, but now is not the time for most users to buy it.

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 versions of the devices are getting smaller in size, compared with the old ones, and have more features. You can use them to scan photos, ID cards and checks, among other things — just so the item is no more than slightly bigger than card size.

I have been testing two products: the OptiCard 821 from Plustek Technology, of Cerritos, Calif., and the IRISCard Pro 4, from Belgium-based Image Recognition Integrated Systems, or I.R.I.S.

Plustek’s OptiCard 821

I found that both scanners have a quick and easy way to organize business-card information, but their software isn’t as easy to work with when manipulating the resulting digital images. Also, the machines work best at their originally intended task, and so are better at scanning business cards than at scanning photos, for example.

The software in both devices, overall, created clear images of the names and numbers from most of the typical cards; that is, those cards written with dark ink against a light background. The scanners did a poor job when they had to read cards that were printed on dark-colored stock.

Installing the software was easy enough, and took only a few minutes. After inserting the software CD into your computer, small pop-up windows open to guide you through the process. When the installation is finished, you connect the scanner to your computer’s USB port with the cord provided.

To begin scanning, you just feed the cards into a front slot on the devices and push the scan button. The scanners pull the cards across the scanning head and spit them out the back, saving the cards in the process.

The first time you use the scanners you will be asked to calibrate them to set the parameters for color, shadows and light. It’s an easy task: You just insert a special card that comes with the packages.

The scanners’ software can recognize and categorize cards written in several languages, including Spanish, French, German, Italian, Arabic and Chinese. Scanning a business card using either machine didn’t take more than five seconds; photo-scanning took much longer.

Both machines have two buttons on the top for scanning and for further customizing the scan. The scan buttom has a few standard configurations for capturing the image from the card and transforming it into a PDF file.

The custom button begins with the same process, but then allows you to manipulate the results. When I inserted a card into one of the scanners and pressed the custom button, a window pop-up opened for me to choose details such as language, color, dimensions, the specific file to which I wanted to send the image and the storage format.

You can edit the cards as you store them and make any fixes you might have from botched scans. The images are saved in the folder you chose when you configured your scanning options. You can opt to arrange them just alphabetically, too.

The scanners come with software that can help make the scanning and organizing process more efficient, but could also be a bit confusing for some users because of all the choices.

To test the new OptiCard, which costs $150, I processed 20 random business cards with white backgrounds. I found that scanning was swift; 13 white-background cards came out perfectly or with such minor glitches that they didn’t require any editing. An additional four needed some editing but fixing them didn’t take more than a few minutes. Three cards needed major retyping, replacing missing numbers and redoing a name that got scrambled into a phone number.

I also tried scanning two dark-background cards but to no avail. One didn’t come out at all and the other had black splotches.

I found the $200 IRISCard Pro 4 slightly more accurate in scanning textual information from the same 20 cards. Only two needed minor editing — replacing a hyphen with a comma, for example — and just one card required major retyping, replacing skipped information. The scanner, however, was no better at the dark cards.

I also scanned a couple photos in both devices, but the copies were too blurry to save.

Both scanners are smaller than many TV remote controls. The OptiCard is 1.5 inches high, 6.9 inches wide and 2.4 inches deep. The IRISCard Pro 4 is 1.3 by 6.2 inches and is two inches deep. I was able to take them to work in one of my jacket pockets. I could imagine bringing the device along for a days-long seminar to keep up with card-collecting. Both are compatible with Windows PCs and Macs.

While the interface between the scanners and the user’s contact data program could offer more features to make organizing easier, these tools are worth a try. At least you can get those cards off your desk before the pile topples.

• Email me at sarmad.ali@wsj.com. Walt Mossberg is on vacation.

But in recent weeks, I’ve been bombarded by reader emails asking for Mac-buying advice. So, here’s a quick guide — a sort of Mac FAQ — to shopping for a Macintosh. As with my Windows guides, this is aimed at average, mainstream users doing typical tasks, not techies or businesses or hobbyists.

Q. Who should consider a Mac?

A. Pretty much every average consumer using a computer should at least look at the Mac. It combines gorgeous hardware with an operating system I consider superior to Windows, with better built-in software. It can even run Windows programs if you buy and install a copy of Windows. And unless you do that, you won’t be vulnerable to the vast array of viruses and spyware that threaten Windows users. Only a handful, so far, have been written to run on the Mac operating system, OS X.

Q. Who shouldn’t consider the Mac?

A. People who spend much of their time playing cutting-edge games should stick to Windows computers, because there are far fewer games written for OS X. Apple doesn’t offer hardware tuned for serious gaming. People looking for the lowest-price PCs should also avoid the Mac, because Apple’s cheapest model, the Mac Mini, costs $599.

Another group that should shun Apple’s computers are people who depend for support on corporate IT departments that are either ignorant about, or hostile to, the Mac. Finally, if you know and like Windows, and expect mainly to use Windows programs, stick with a Windows PC.

Q. Can I run Microsoft Office on a Mac?

A. Yes. Microsoft makes a Mac version of Office, which uses the same file formats that Word, Excel and PowerPoint for Windows have used for years. A new version of Office for the Mac is due in January and it will handle the new file formats Microsoft introduced this year. But the Mac version of Office omits Outlook. It has a similar program called Entourage, but Entourage can’t use Outlook data files. If you want a Mac but must have Outlook, you will have to install Windows.

Q. Can I use all my Windows files on a Mac?

A. Out of the box, Macs can handle all the common file types Windows machines create, including text files, pictures, songs and Adobe PDF files. The Mac even comes with a simple word processor that can open Microsoft Word files.

However, some specialized Windows programs create files that the Mac can’t handle out of the box. And the Mac version of Quicken has a difficult time properly handling Windows Quicken files. If you are a Quicken fan, install Windows and run the Windows version.

Q. Can I mix Macs and Windows on the same home network?

A. Macs can plug and play with most brand-name wired and wireless routers, and can share Internet connections with Windows PCs.

Q. How are Macs at Web surfing?

A. Fine. Apple’s built-in Safari browser is very good and the Mac version of Firefox is essentially identical to the Windows version. However, Macs lack an up-to-date version of Microsoft’s Internet Explorer, so you will have to install Windows if you need IE.

Q. Can Macs run standard peripheral hardware?

A. Macs can run nearly all keyboards, mice and printers that use USB connections, even ones that don’t explicitly say they run on Macs.

Q. What desktops does Apple offer for consumers?

A. Apple’s main consumer desktop is the one-piece iMac, which I regard as the best consumer desktop on the market. It comes in four models, with built-in 20-inch or 24-inch, flat-panel screens at starting prices ranging from $1,199 to $2,299.

Q. How about Mac laptops?

A. There are two. The entry-level MacBook has a 13-inch screen and a starting price of $1,099. The high-end MacBook Pro comes with either a 15-inch or 17-inch screen and starts at $1,999. Apple currently doesn’t offer a smaller laptop for road warriors, but there are persistent rumors that it will do so soon.

Q. What minimum specs should I look for on a Mac?

A. All Macs come with at least one gigabyte of memory — twice the minimum required for the new version of OS X, called Leopard. If you can, get two gigabytes. Apple charges a lot for extra memory, but you can buy it for less at stores and online providers.

Macs use the same dual-core Intel processors and graphics systems as many mainstream Windows computers; and, as with Windows, I wouldn’t pay extra for greater processor speed.

The iMac comes with at least a 250-gigabyte hard disk, and Mac laptop hard disks start at 80 gigabytes. Mainstream Windows desktops typically start with larger hard disks. But Apple offers much larger disks as options, which you should consider if you store a lot of photos, music and video files.

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.

Just use an Internet-based service so that you can chat from a Web page without having to install any software, which might be blocked by a firewall. I tested two such services: Meebo at www.meebo.com and KoolIM at www.koolim.com. Both are free.

These services let you simultaneously log in to multiple IM accounts — and communicate with people with various services. If you have a friend who uses Yahoo Messenger, for example, and another who likes MSN Messenger, you can chat with either.

Another plus: Meebo and KoolIM are far less vulnerable to viruses than downloadable applications. They’re also more efficient, saving users the hassle of installing multiple programs on a computer. This is especially handy for people with old computers that slow down when running several applications.

Meebo has a well-designed, sleek interface that makes it appealing to even the least tech savvy. From its home page, you simply sign in for different IM services—MSN Messenger, Yahoo Messenger, GTalk (or Jabber) and AIM (or ICQ). Your buddy list will be combined automatically. You don’t have to register, but if you do, you get perks such as a single sign-on for all of your accounts, and the ability to share files, save chat logs and store conversations.

I tried Meebo on my work Windows PC and my iBook at home, and it worked well on both. To start chatting, you just log in to any of the IM services by entering the screen name and password you already have with a service, or by picking a new name, password and services. Your buddy list will appear in a window on the right side of the page, with each name marked by an icon denoting the service the person uses. Once in your buddy list, you can add or delete a contact, message or join a group chat.

The service also offers MeeboMe, a way to chat from your own Web site. Bloggers can use this to start a conversation with site visitors who log in to their Meebo account. It also shows how many users are on the site at any time.

But Meebo, like most such Web services, lacks the ability for audio and video chats — basic features on installed IM software. If you’re used to plugging in a Webcam and headgear to chat with friends, these services might not be for you. Meebo also doesn’t have the standard send button that’s on installed IM software. Instead, you press a key on your keyboard.

Sharing files using Meebo is tricky, too. Only Meebo account holders can send files; although anyone can receive them. When I sent a PDF file to my friend on her installed MSN Messenger, she received a message and a link that rerouted her to Meebo’s home page with no further guidance. When I sent her the same file after she logged in to her MSN using Meebo, she could open the file.

KoolIM also connects users to multiple IM accounts from one Web page. It gives you the option to create an online account, so you don’t need separate log-ins for each IM service you’ll encounter.

You can select an embedded or a pop-up version of the service. The embedded version shows your buddy list and messages as windows tied to a Web page, while the pop-up version lets you move the windows around the screen. You can choose to display all of your buddies or only the ones online. In your buddy-list window you can add and delete names and log in to or out of a service.

I didn’t like having text ads appear at the bottom of the IM window in KoolIM, or the fact that, unlike Meebo, there isn’t a time stamp on messages to tell you when they arrived. It also doesn’t allow you to send files, as Meebo does. And it doesn’t let you save conversations or chat logs. KoolIM’s lack of some of these basic features might make it less appealing to consumers, especially those who ponder swapping it with their desktop software.

I preferred Meebo, but both services are good alternatives to installed IM, if you’re willing to do without audio and video features.

Walt Mossberg is on vacation. Find all my columns and videos online free at the new All Things Digital Web site, http://walt.allthingsd.com.

• Email me at Sarmad.Ali@wsj.com.