Corporations may have deeper pockets than consumers, but they also have more at risk with major upgrades like an operating system. "Consumers may want the latest and greatest, but businesses are generally more conservative," said Michael Silver, an analyst with Gartner.

Microsoft, naturally, is a huge Vista user, with the OS now running on more than 60,000 PCs, according to Tom Ryan, senior PR manager. The company is trying its best to to follow suit, touting Vista's as areas of potential savings for companies.

But most companies aren't likely to deviate from their normal routine -- extensive pre-upgrade testing that can take more than a year, and staggered three-to-five-year cycles for replacing hardware, Silver said.

"More than half of our clients are telling us that they're only bringing in Vista as part of their regular hardware refresh," Silver said. Indeed, he expects many corporations next year to exercise the "downgrade rights" in their Software Assurance contracts with Microsoft. That will let them order new PCs with Windows XP Professional, which they can upgrade to Vista in a few years when they are truly ready to move.

As a result, Gartner expects 22 percent of PCs sold next year to come with Windows XP Professional. Most companies won't start moving towards Vista until 2008, when 52 percent of new PCs worldwide are expected to ship with a business version of the OS, according to Gartner.