XP also was released before the majority of PCs in enterprises were laptops, and both Vista and Windows 7 have features that allow IT managers to better manage and secure laptops and mobile devices for the type of mobile workforce found in many enterprises today, Schuster said.

"When you think about Windows XP in that context -- it came out in 2001, when less than 10 percent of devices were laptops," she said. "There wasn't ubiquitous broadband. There weren't the levels of compliance and regulatory requirements. There weren't data protections."

What may be surprising in Microsoft's message, however, is that the company doesn't care which of its newer OSes customers move to -- Windows Vista or Windows 7 -- as long as they do what's best for their individual IT environments.

"What strikes me is that Microsoft is being fairly pragmatic about what the options are for customers," said Al Gillen, an analyst with IDC. "Microsoft seems to recognize the reality that customers aren't going to do what Microsoft tells them to do. They're going to do what's right for them."

Indeed, Schuster said Microsoft is "agnostic" about which OS customers upgrade to. She said Microsoft is just trying to set expectations for any upgrade that may be planned or in progress, so that customers aren't surprised by problems or complexities they may encounter.