This contrast has appeared sharper in recent years, as Microsoft’s Windows Vista operating system received a tepid critical response compared with Apple’s Leopard platform and as the company’s Live Web search service has slipped further behind Google’s. In addition, Microsoft’s cellphone software, Windows Mobile, looks old and creaky compared with Apple’s sleek iPhone and Google’s forthcoming Android mobile operating system.

But innovation does exist at Microsoft’s sprawling Redmond, Wash., campus. For instance, last year’s daring and radical redesign of Microsoft Office has been a critical and commercial success.

Now, there’s a sort of guerrilla team inside Microsoft designed to churn out innovative products more often and more rapidly. Called Live Labs, the unit is a small operation that aims to turn technology theories into real, Web-based products relatively quickly. It has only about 125 employees, and even that modest number is broken up into smaller teams tackling specific projects.

This week, Microsoft Live Labs is releasing its first broad consumer Web service, called Photosynth. This service turns multiple photos of a scene or site — say, an art gallery or a building — into a 3-D scene you can virtually “walk” through on the Web.

Unlike a simple 2-D panorama, which many photo programs can create from several pictures, a Photosynth creation, called a “synth,” is a virtual 3-D environment. It gives you the feeling you are in the middle of a room looking around, or circumnavigating a building or object. You can travel through a scene both laterally and vertically, and zoom in to see detailed, higher-resolution views of objects inside the synth, such as paintings on a wall.

For instance, you don’t just see a long, flat picture of Stonehenge or the Grand Canal in Venice. You are made to feel you are there, moving through these places, looking up at the sky or down at the ground, and pausing to examine more closely a particular stone, boat or building.

Such 3-D walk-through images have been around for awhile; they are used on some real-estate Web sites, for example, to show houses virtually. But Photosynth allows anyone to create them using any standard digital camera, and even using pictures you already possess that weren’t created with Photosynth in mind. You could even use photos of the same site taken by several people. The software will analyze the pictures, figure out which ones overlap and in what order, and then turn those shots that match up into a 3-D synth.

Photosynth, based on technology Microsoft acquired in 2006, is entirely free, and it’s entirely based on the Web, at photosynth.net (where it will be launched at midnight EST Thursday). At that site you can view not only your own synths, but the synths created by every other Photosynth user.

I’ve been testing this service for about a week, and while it has its flaws, I believe that Photosynth offers a dramatic new way to use your photos and to share them with others.

Photosynth works within a Web browser, using a small plug-in you install. Currently, it works only in Windows, using Microsoft’s own Internet Explorer browser or its rival, Firefox. A Macintosh version is in the works, but for now, you can’t even view others’ synths in the Mac operating system.

When Photosynth works right, the results are wonderfully satisfying. But it takes some skill to get a set of photos the service can match up well, a quality Microsoft calls being “synthy.” Ideally, portions of each slice of a 3-D scene should show up in at least three photos, with 50% overlap between them. After you upload your pictures and Photosynth does its best to make them into a 3-D scene, the service assigns them a percentage number that indicates how synthy they were.

In my tests, I tried both collections of photos I already possessed and some I snapped with Photosynth in mind. My pictures of a piazza in Verona, Italy, were only 38% synthy, while ones I took of a hotel room specifically for Photosynth use were 73% synthy.

One gripe I had was that Photosynth doesn’t tell you how synthy your pictures are until after you have uploaded them and waited until the system merges them, a process that can take a long time over a slow Internet connection. It would be much better if the service could tell you in advance how synthy the pictures are. Another objection is that Photosynth has no privacy settings. All your synths are open to viewing by everyone who uses the service.

But, overall, Photosynth is an impressive new way to view and share photos, and an encouraging sign that innovation and creativity still live in Redmond.

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.

While the Windows and Mac user interfaces are broadly similar, they do have subtle variations in day-to-day use that require some re-education for switchers. And because there are so many fewer Mac users than Windows users, help from friends and co-workers can be harder to obtain than it is for people switching the other way, to Windows from Mac.

So, here’s a quick tip sheet explaining a few of the most common differences in the daily use of Windows XP (MSFT), from which most people would be switching, and Apple’s (AAPL) Mac OS X Leopard, which switchers would be adopting.

This column isn’t an argument for making the switch to a Mac, merely an attempt to help those who have done so, or who are considering doing so. Of course, all Macs currently sold can run Windows and Windows programs concurrently with the Mac operating system. But this guide is for folks who intend to use their Macs primarily with Leopard, not Windows.

Menu Bars: In Windows, each program typically has its own menu bar. On the Mac, there’s a single menu bar at the top of the screen that changes, depending on which program you are actively using.

Task Bar: The equivalent of the Windows XP Task Bar on the Mac is the Dock. Unlike the Task Bar, which primarily holds icons representing open windows, the Mac Dock primarily holds icons of programs you use most often. To place a program onto the Dock, you just drag its icon there. To remove it, you just drag its icon off the Dock and it disappears in a puff of animated smoke.

Start Menu: There is no Start Menu on a Mac. Its functions are divided between the Dock and the Apple menu at the upper left of the Mac screen.

Control Panel: The Mac equivalent of the Windows Control Panel is called System Preferences, and it can be launched from either the Dock or the Apple menu.

Keyboard shortcuts: Common Windows keyboard commands, such as Ctrl-S for Save, Ctrl-P for Print, and many others, are also available on the Mac. However, instead of using the Control key, they use the Mac’s Command key, which bears either a cloverlike symbol or an Apple logo. So, on the Mac, for instance, Command-S is for Save.

Quitting programs: In Windows, you can quit a program by clicking on the red “X” in a square at the upper right corner of the window you’re using. But on the Mac, if you click on the equivalent button — a red “X” in a circle in the upper left corner — you are merely closing the window, not quitting the program. To quit the program, you must either select Quit from the leftmost menu or press the Command and “Q” keys together.

Maximizing windows: When you click on the blue maximize button in Windows XP, the window you are viewing occupies the whole screen. In Leopard, the equivalent button — a green circle at the upper left — increases a small window’s size to a footprint deemed optimal for its contents, which isn’t always the whole screen.

Switching programs: One common way to switch among running programs in Windows XP is to press Alt and Tab together. This displays icons of each running program and allows you to switch among them. On a Mac, the same trick can be performed by pressing the Command and Tab keys together. The Mac also has a terrific feature called Expose, which shows every open window at once, in miniature form, so you can navigate among them. You can trigger Expose in a number of ways, but the most common is to hit either the F9 key or the dedicated Expose key, depending on your Mac model.

Right-clicking: Contrary to common belief, the Mac has a right-click menu function, just like Windows. Most desktop Macs now come with a mouse that allows right-clicking, and you can use almost any two-button USB mouse with any modern Mac. If you are using a Mac laptop, which has only one button under the track pad, you can simulate a right-click by either holding down the Control key when you click, or by placing two fingers on the track pad while clicking. The latter technique, which I favor, must first be turned on in System Preferences.

Screen: Your desktop picture and screen saver on a Mac are set via a System Preference called Desktop & Screen Saver. Screen resolution is set in the Displays System Preference. In Windows XP, all of these things are included in the Display control panel.

For more information, Apple offers two Web sites. One is called Mac 101, and is at apple.com/support/mac101. The other is called Switch 101, and is at apple.com/support/switch101.

• 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.

So, last month, the photo giant introduced Photoshop Express, its free Web-based service for storing, sharing and editing photos, in an effort to compete with established online photo services such as Yahoo’s (YHOO) Flickr, Google’s (GOOG) Picasa Web Albums, or the photo-laden Facebook social-networking service.

Photoshop Express has many of the same features as Flickr and its ilk. It gives you two free gigabytes of photo storage. But Adobe is hoping to make its mark with editing.

Most online photo services offer little or no editing, assuming you’ll do that using software on your computer before you upload your pictures. But Photoshop Express, borrowing from Adobe’s deep knowledge of photo editing, offers the nicest set of Web-based editing tools I have seen. They are sophisticated for a consumer application, yet easy to use. They edge out those in Picnik, a pioneering Web-based photo editor I hailed last year.

These slick editing tools are not only available for use with photos you’ve uploaded from your hard disk. You can also use them to edit pictures stored in your accounts at Facebook, Picasa Web Albums and another big photo-storage service, Photobucket — all without leaving Photoshop Express. You can even move pictures between Photoshop Express and these three services just by dragging and dropping.

Adobe’s new service is available in the U.S. only, at www.photoshop.com/express.

I’ve been testing Photoshop Express and its service overall is pretty good, even though it’s still labeled “beta.” It’s a nice example of the Web 2.0 trend, where programs accessed via a browser can look and feel like applications that live on your computer.

But Photoshop Express is rough around the edges. It can be slow at times, and it’s missing some obvious features, like the ability to easily download publicly shared pictures from other members or to print photos. Adobe says it is working on these things.

Photoshop Express isn’t meant to replicate all the features and power of Photoshop. It’s more like a Web-based version of Photoshop Elements, Adobe’s consumer software package.

I tested Photoshop Express on multiple computers: PCs running Microsoft’s (MSFT) Windows XP and Windows Vista, and Macs running Apple’s (AAPL) Leopard operating system. I used it in all three major Web browsers: Internet Explorer for Windows, Firefox on both Windows and Mac, and Safari, also on both platforms. It worked fine in all of these operating systems and browsers, though it does require Adobe’s free Flash software.

For my tests, I uploaded from my computers dozens of photos, from very large images captured with good digital cameras to smaller shots from cellphones. All were handled perfectly by Photoshop Express. I also opened and edited pictures in Photoshop Express from my accounts on Picasa Web Albums and Facebook. All of this worked well, though uploads of large images can be slow if your Web connection is pokey.

Photoshop Express is a handsome product, presenting your photos on a gray background with controls and features arrayed at the top and bottom, and down the sides, in a logical, clear manner. Your own photos are presented in a section called “My Photos,” and can be organized into albums. Photos that other Photoshop Express users have chosen to publicly share are organized into collections called “Galleries,” which can include multiple albums. You access these community photos by simply clicking on “Browse” or performing a search.

For each album you create, you can choose to share it publicly or to keep it private. Whichever option you choose, you can email friends either a link for viewing the album or a single photo. Your own photos can be downloaded at a variety of resolutions, including original size.

When you view shared galleries or albums, they appear as slide shows. You can select a number of slick effects by which the slides appear, allowing them to zoom and glide into place from various directions.

The editing features really stand out. In addition to standard tools such as auto-correction and red-eye elimination, Photoshop Express lets you touch up areas; adjust exposure, saturation, and lighting; and even make certain colors pop — so grass is greener, for instance. And, in most cases, it shows you small example images illustrating the changes, then previews those changes in the larger main image just by moving your mouse over the example. You can revert to your original at any time.

Unfortunately, there are a number of problems. Photos, especially large ones, can take awhile to appear in the editing module and to snap into focus. Captions sometimes get lost or mixed up when you move photos to other services. You can view shared albums only as slide shows, not as individual photos.

Still, Adobe has made a good start with Photoshop Express, and it’s worth a try if you want better online editing for your pictures.

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.

As always, this is a general guide aimed at mainstream, nontechnical consumers who dwell on common tasks such as email, instant messaging and surfing the Web; managing and lightly editing photos, videos and music; and using basic office applications. It is not intended for heavy gamers, video producers or corporate buyers.

There’s a vast variety of laptop models, but this guide is meant to cover the most common types of laptops, those with screens from about 12 inches to 17 inches, and weights ranging from around 2.5 pounds to 7 pounds.

For this column, I’m not including the category of tiny machines now called netbooks, with screens under 10 inches. I am also ignoring the huge, heavy laptops with screens larger than 17 inches that are primarily aimed at gamers.

Even the remaining mainstream machines range wildly in price, from bargain-basement models at $350 to high-end ones that can top $3,000. In my experience, the top brands for technology and reliability are Apple and Lenovo’s ThinkPad line, but various models from Sony, Hewlett-Packard, Toshiba and Dell are also worth investigating.

So, here is a quick guide to the key factors you should consider when buying a laptop.

Size: If you are a constant traveler, think about the subnotebook models, which generally weigh 3 pounds or less. There are two types of these. The classic subnotebook has a small screen, 12 inches or less, and a cramped keyboard. This year, a new type emerged, with a full keyboard and a normal 13.3-inch screen packed into a thin, light body. There are two of these: the MacBook Air from Apple and the Lenovo ThinkPad X300. All subnotebooks are relatively costly, typically ranging from $1,500 to over $3,000.

If your laptop will mostly stay at home, the office, or in class, a 5-7 pound machine with a screen of either 13.3 inches or 15.4 inches is the best bet. A well-equipped model in this class is likely to run you between $800 and $1,200. Typical models in this class are the Dell Inspiron 1525, the HP dv6700 and the Apple MacBook.

Windows vs. Mac: This is the eternal question. In my view, Apple’s Leopard operating system is faster, better and far less prone to malicious software than Microsoft’s Vista operating system. And the Mac laptops also come with better built-in software. The $1,099 MacBook is a solid, fairly priced machine, and the $1,999 MacBook Pro is even better. Both also can run Windows.

But Windows laptops are often less expensive, tend to have a greater variety of ports and slots, and come in more styles and sizes.

Apple’s MacBook

Operating system: If you are buying a Windows laptop, be aware that Vista is slower than Windows XP, in my experience, and still has compatibility issues with add-on hardware and software. If you’d prefer to stick with XP, you will find that many fewer models are available with it. And Microsoft has decreed that after June 30, mainstream, name-brand laptops will no longer come pre-equipped with XP.

Video: I recommend getting an LED-powered screen, which is brighter and saves power. Also, if you are choosing Vista, or if you do a lot of converting video for use on portable devices, consider getting a laptop with a separate video card inside that has its own memory.

Memory: If you’re buying an Apple laptop, two gigabytes of memory is plenty. If you’re using Vista Home Premium, I’d consider three gigabytes for best performance.

Processor: Any dual-core processor will be fine. Don’t pay a penny extra for faster processor speed.

Storage: In a mainstream laptop that will be your main computer, look for a 160-gigabyte hard disk or larger. A new kind of storage, called SSD, or solid state disk, is now available. But it is still way too costly for most users, and at the moment is available only in smaller capacities.

Battery life: Many laptops today rarely spend time away from an electrical outlet. But if yours will, look for a battery life of at least three hours between charges.

Wireless: Make sure your new laptop has the new, faster “N” version of Wi-Fi built in. Many cheaper laptops don’t. You can also get a cellphone modem built in, but they are costly and carry a monthly fee. You can always add an external cellphone modem later.

Other features: A built-in camera and microphone can be quite useful, and so can a feature on some Windows machines that allows you to play music and videos without fully booting up the computer.

Don’t let yourself be swayed by sales pitches, or by fanaticism for or against Windows or the Mac. Think hard about how you use your computer and what your budget will allow, and stick to those priorities.

• 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.

Time Machine is a key selling point for Leopard and the Mac. It is more complete, and yet simpler, than the built-in backup feature in Vista Home Premium, the most popular home version of Windows.

But Time Machine has a major drawback: It works much better on desktop Macs than on laptop models. That’s because it’s primarily designed to operate with backup hard drives you connect directly to the computer. And it’s a pain to plug a backup drive into a laptop, which can move around the house. While Time Machine will work with a remote hard disk under certain circumstances, that option requires a second Mac running Leopard, a costly condition.

Now, Apple (AAPL) has attempted to fix the problem with an unusual new companion product called Time Capsule. This is a $299 stand-alone networked gadget that packs both a giant hard disk and a speedy Wi-Fi wireless router into one slender case. It just plugs into your existing home network, and any laptop within wireless range can connect to it. It can back up multiple computers.

Time Capsule is designed to seamlessly work with Leopard’s Time Machine. But it can also be used as a wireless Internet connection, and/or a remote hard drive, for manually storing and retrieving files by Windows PCs running either Vista or Windows XP, or by Macs running Apple’s older Tiger operating system. And you can also use it with certain other backup programs, such as the ones built into Windows XP or Tiger.

In my tests over the past week, Time Capsule worked well in all of these scenarios. However, Time Capsule isn’t meant to do as many different tasks as some other networked drives.

Apple stresses that Time Capsule is a limited, targeted device meant primarily for backup — especially with Time Machine — and as a wireless base station. Unlike some other networked storage devices, like Hewlett-Packard’s MediaSmart home server, Time Capsule doesn’t allow users to simultaneously stream music or videos to multiple PCs, to easily access its contents via the Web or to stream videos to TV sets.

The $299 Time Capsule model comes with a 500 gigabyte hard disk inside, and there’s also a $499 model with hard disk that can hold one terabyte of data, or roughly 1,000 gigabytes. Both models use the same “n” class of Wi-Fi, the fastest version with the longest range. Both also work with computers equipped with the older “g” and “b” versions of Wi-Fi.

You can buy networked hard disks in these sizes for less money and simply use them with your existing Wi-Fi router. However, Time Machine won’t work with them, according to Apple. The company says the only standalone networked hard disk Time Machine can use is Time Capsule.

In my tests, Time Capsule performed perfectly with Time Machine. It also was easily recognized by several of my Windows machines running Vista and Windows XP. On all of these machines, I was able to speedily access the Internet via Time Capsule. Time Capsule can be set up to either replace or supplement your existing Wi-Fi router.

All the machines, even the Windows ones, also could recognize the Time Capsule as a remote hard disk, and save files to it and retrieve files from it. For instance, I manually copied a song, a photo and a Word document from a Mac laptop running Leopard onto the Time Capsule. On a Dell running Vista, I then opened the Time Capsule and launched that same Word document in the Windows version of Word, opened the photo in Vista’s Photo Gallery program, and played the song in Windows Media Player. This same process worked in reverse.

Apple doesn’t guarantee that Time Capsule will work with all backup programs. But it says it will work with the backup software built into Tiger and will likely work with some other backup software.

In my tests, the built-in backup program in Windows XP Pro worked fine with Time Capsule. But the built-in backup program in Vista failed. Microsoft said the problem I encountered was due to a new Vista security feature for backups that foils some remote hard disks, not just Apple’s.

Setting up Time Capsule was easy, using a step-by-step utility program that Apple supplies in both Mac and Windows versions. The device has a USB port that can be used to add either an additional hard disk or a networked printer. And it can be connected to a network via a wired connection if you don’t want to use its wireless functionality.

If you use Time Machine on a Mac laptop, then Time Capsule’s $299 price is money well spent. If you don’t, there are cheaper or more versatile solutions to the backup problem.

• 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.