"We consider XP SP2 to be a major release because of the nature of the enhancements," one IT manager told Computerworld in 2004. Such opinions prompted many companies to block updates to SP2 on their PCs for months until they could prepare for the mammoth upgrade.

Another Forrester report, by a different analyst, cites a "new trend" of upgrades from XP to Vista -- and says that skipping Vista to wait for Windows 7 would be a mistake.

Some of the reasons cited for Vista's supposed doom are unique to the new operating system. There's the widespread exercising of downgrade rights by users who purchase PCs with Vista but then revert to running XP. Mac OS X has taken some market share away from Windows over the past year. Cloud computing technologies offer new competition. And the scheduled 2010 arrival of Vista's successor, which Microsoft is calling Windows 7, looms on the horizon. Both Steward and Bowden said they will likely skip Vista entirely and wait for Windows 7.

But other strikes against Vista are ones that XP has also faced and overcome, such as a tottering economy (the dot-com bust, in XP's case), the belief that it was a piece of "bloatware," accusations of price gouging by Microsoft, and apathy or revolt by end users.

For most users, "change is always bad," said Merrie Wales, information systems manager in the human resources department in Glenn County, Calif. Wales, who oversees 250 desktop PCs, said that only a tiny portion of her users welcomed a move to Vista this spring. But, she noted, a similar sliver of users was happy when the agency finally upgraded to XP in 2006.

And the Vista rollout "has turned out much better than we anticipated," Wales said. "It's not a bad OS. There are big improvements under the hood."

There also are other factors that brighten the long-term outlook for Vista.

1) Virtualization is easing compatibility problems

Like Vista, Windows XP has an application compatibility mode that simulates older versions of Windows. But it's not perfect. And Vista gives more options to IT managers who are stymied by drivers or applications still breaking.

For instance, Glenn County runs Vista in standard mode, instead of administrator mode, on all of its PCs for security reasons. But the human resources department had a key application that could run only in administrator mode. To solve that problem, Wales said she used Microsoft's application virtualization technology to create a self-contained app package that runs as an administrator inside a virtual machine but doesn't require end users to possess admin credentials.