The installed base will continue to lag, though. Only by the end of 2009 will the numbers of PCs running a business version of Vista equal those running Windows XP Professional.

In addition to companies unwilling to budge from their standard PC upgrade cycle, most are loathe to tinker with existing hardware, no matter what Total Cost of Ownership (TCO) savings Microsoft promises.

That's why companies such Sasfin and FranklinCovey Co. are such rarities. To get all 750 of its PC-using employees onto Vista next year, the Salt Lake City time management products maker plans to add RAM to about two-thirds of its PCs while replacing the rest, according to Dan See, director of infrastructure at FranklinCovey.

The company, which participated in Microsoft's Technology Adoption Program (TAP) for Vista, has its limits. See has no plans to upgrade the video cards in existing computers, which he acknowledged might prevent employees from taking advantage of Vista's Aero 3-D "glass" interface. "The video features are nice, but the expense of updating all of the video cards is prohibitive," he said.

Some companies are moving forward on Vista to stay ahead of the pack.