Enterprises now in the midst of migrating to Windows 7 are unlikely to repeat that same work in just two years with Windows 8, an analyst said today.

"They would certainly like to upgrade only to every other edition," said Michael Silver of Gartner, referring to businesses. "If Windows 8 comes out in two years, I think that's likely to happen, that many [enterprises] will be very suspect about migrating to the next release."

Silver's comments came after the Dutch arm of Microsoft announced that the follow-on to Windows -- dubbed "Windows 8" by most, if not by Microsoft -- will ship in two years, or in 2012.

That timeline fits earlier Microsoft statements that said Windows is on a three-year development plan.

The remark about Windows 8 -- "Microsoft is on course for the next version of Windows. But it will take about two years before 'Windows 8' [is] on the market," the Microsoft Netherlands blog stated Friday -- has since been scrubbed from the post. Tom Warren of Neowin.net was the first to report on the Dutch posting.

The fact that Microsoft scratched the Windows 8 reference came as no surprise to Silver or Michael Cherry, an analyst with Directions on Microsoft, a Kirkland, Wash. research firm that tracks only Microsoft's moves.

"If Microsoft starts talking up Windows 8 now, it risks slowing momentum for Windows 7," said Cherry in an e-mail reply to questions.

Windows 7 does have momentum on its side: Last week Microsoft said it has sold more than 240 million licenses to the one-year-old operating system, making it the fastest-selling OS in the company's history.

Web metrics company Net Applications has also noted the fast pace of Windows 7 adoption. According to its statistics, Windows 7 reached a 17% usage share in just one year, more than twice as fast as did the problem- and perception-plagued Vista.

But the three-year development cycle that Microsoft seems committed to will present problems for companies, if not consumers.

Fatigue, for one thing, said Silver, who cited the slow uptake for Office XP, which appeared just two years after its predecessor, Office 2000, as an example. Companies tire of migrating to fast-paced operating system upgrades, largely because of the number of critical applications that may or may not run on a new edition.

That's one reason enterprises generally seem more willing to upgrade if the new version is a "minor" update, or one that doesn't introduce a new architecture, but resist a so-called "major" upgrade. That was one of the reasons why Vista never got traction in business, said Silver.

"So it will depend on whether Windows 8 includes major architectural changes, or if it's more of a polishing release," Silver said. "If it's the latter, it will be kind of hard to skip. But if it's a major release, Microsoft will have a hard time selling [Windows 8] to the enterprise. They saw that when [companies] skipped Vista and stayed with XP."

Microsoft once touted a major-minor-major development cycle for Windows, but it's unclear whether that is still its plans. "Microsoft likes to call every release 'major,'" noted Silver.

However, Silver pegged Windows 7 as a minor release, more of a polish of Vista than a sea change as Vista was compared to Windows XP. He also expects Windows 8 to be another minor release.

"They have to be very careful that they don't stall Windows 7," he added, echoing Cherry.

Last week, Microsoft CEO Steve Ballmer told an audience at the Gartner Symposium that the next version of Windows was the firm's "riskiest bet" for the future.

Silver, who was at Symposium, said Ballmer may have been alluding to the risk Microsoft is taking with a three-year development cycle, and possible resistance to migrating. Or he could have pegged Windows simply because the operating system represents such as large part of Microsoft's revenues.

"Microsoft would love to have a new version of Windows out every Christmas," said Silver. But that won't happen, not with the company forced to appeal to not only consumers -- those who would conceivably be motivated to buy new PCs if Windows changed annually -- but to its more conservative customers.

"I think Microsoft faces a real dilemma with Windows 8," said Cherry. "They don't have a good track record at delivering Windows client versions on a reliable and predictable schedule, something that corporations need in order to plan desktop deployments and refreshes correctly. And Windows 7 is a good operating system ... it is reliable and works well."

Pushing Windows 8, in Cherry's eyes, would be a mistake. But if it is hewing to a three-year development cycle, Microsoft has to be well into Windows 8 by now. "Realistically, they have to be locking down Windows 8 features soon to have sufficient time for development and testing," he pointed out.

Microsoft declined to comment on Windows 8, development plans for the next edition or on the since-deleted aside on its Dutch site.

Gregg Keizer covers Microsoft, security issues, Apple, Web browsers and general technology breaking news for Computerworld. Follow Gregg on Twitter at @gkeizer or subscribe to Gregg's RSS feed . His e-mail address is gkeizer@computerworld.com.