Microsoft's new tablets will arrive in two versions. Which is right for you?

The Surface Pro promises ro­­bust computing in a slimmed-down package. We haven’t seen any real Windows 8 software yet, so there we must withhold judgment. But Surface Pro will be able to do anything a desktop or laptop can do today, and it will have a serious laptop processor, the same Intel Core i5 as on an Ultrabook.

If casual computing—Web browsing, email, social networking, and video streaming—is all you need, Surface RT should suffice. It will run an ARM-based Nvidia Tegra 3 processor that requires less power to operate than Intel processors do. But Windows RT can’t run in desktop X86 mode, so you can’t use your existing software on it—you’re limited to running apps that will be available from Microsoft’s Windows Store.

And that leads to our next question: What apps will be available?

Surface Apps: What to Expect

Surface RT relies on the new Metro interface of Microsoft’s Windows 8. That means you can’t use your existing desktop programs (you can do that only on Surface Pro); you’ll have to buy all-new Metro apps from Microsoft’s Windows Store, and that will be the only way to get Metro apps.

Microsoft is making a big push with developers to have big-ticket apps available at Windows 8’s launch. Box.net, ESPN, Netflix, and USA Today have apps well under way, and traditional Windows software companies are planning to have programs available for Windows 8 Metro, too. Microsoft itself will include a Metro version of its Office apps with the Surface RT tablets. But many software makers have stayed quiet on their plans, and it’s not clear whether Microsoft will have a critical mass of desirable and popular apps available at launch.

The company says its Windows Store will filter apps based on the device you’re using, so you can get just the apps that will run on your device. You can install purchased apps on up to five machines­—tablet, laptop, or desktop. This multidevice flexibility gives Windows tablets like Surface a substantial advantage over competing tablets running iOS or Android.

How much will these and other apps cost? For Surface to be competitive, apps must be relatively cheap, following the models of Android and iOS. For many Windows developers, that will require a substantial adjustment.

Microsoft’s Radical Gambit

That Surface comes from Microsoft, and not one of Microsoft’s many PC hardware partners, underscores just how dramatically the personal computing market has changed over the past decade. It marks the first time that Microsoft has produced its own Windows hardware since the company initially began licensing its Windows software 37 years ago.

For Windows 8 to thrive, Microsoft must make sure consumers have viable Windows 8 tablets. While prominent PC makers like Hewlett-Packard target business users with their Windows 8 tablets, Microsoft apparently sees the need to jump-start the consumer market with an eye-catching flagship device. Ultimately, Microsoft will have company; I expect competitors to emerge closer to Windows 8’s launch.

As Apple’s success with its iPad has shown, tablets are a different beast than laptops and desktops. Apple has prevailed in part because it controls the design and functionality of both the hardware and the mobile OS software; the two elements work smoothly with one another and integrate seamlessly into the company’s software ecosystem.

Google—after witnessing a mishmash of uneven Android tablet releases from its hardware partners­—ultimately reached the same conclusion. In July the company, in partnership with Asus, released its own branded Android tablet, the Nexus 7.

With Surface, Microsoft joins the other operating system makers with a tablet offering of its own. Microsoft’s proposition, however, is different from its competitors’. Surface is backed by the full power of the company’s Windows operating system, along with the robust drivers, peripheral compatibility, and inherent software inter­operability that Windows is known for. That you can buy a Metro app in Microsoft’s Windows Store and use it on up to five devices—tablet, laptop, or desktop—is a personal computing Shangri-la that neither iOS nor Android can offer.

Surface could propel the PC into the post-PC era. Add in its own content stores for users to acquire movies and music, and Microsoft has a solid recipe for competing head-to-head against Apple—and against Amazon and Google, too.

Editor's note: Tomorrow, look for "How Surface Stacks Up"—a detailed comparison of the two Surface models against rival products.