For most businesses, the cost of licensing Windows is dwarfed by what it costs to manage the OS and the applications running on their PCs. The bulk of those expenses comes from paying the salaries of IT staffers, according to analysts.

Microsoft claims that enhancements in Vista, such as tightened security, more powerful installation tools and improved central management capabilities, will allow companies to sharply cut the amount of time it takes to maintain PCs. That should lead to big savings, the software vendor predicts.

Lee Nicholls, a senior technology adviser at Microsoft systems integrator Getronics NV, said calculating the potential total cost of ownership savings from an upgrade to Vista can be difficult. He added that operational costs likely will go up immediately after an upgrade because of the need for additional end-user support.

Nonetheless, Nicholls said that based on Getronics' experiences in helping 10 large companies deploy Vista for beta-testing, users can save almost US$320 per PC annually.

But Robert Taylor, CIO of the Fulton County government in Georgia, said he thinks that for organizations like his with lots of full-time IT staffers, such savings estimates likely will turn out to be little more than "funny money."