"We'll probably start testing Windows 7 when Service Pack 1 arrives and get serious [about upgrading] when SP2 comes," Valle said, taking a conservative approach to the deployment.

Smaller customers like Papa Gino's are arguably a bigger problem for Microsoft. Many of them buy the cheaper Select or Select Plus licenses expressly to avoid Software Assurance and don't want to be locked into Windows upgrades they might not ever install.

If a Select licensee belatedly chooses to upgrade to Vista and then, later, Windows 7, it would have to buy Software Assurance at a cost of between US$100 to $165 per PC, according to , an analyst with the independent research firm, Directions on Microsoft.

Schuster, however, argues that the benefits would outweigh the costs. Her rationale:

Companies that skip Vista are at risk of their software makers halting application support on Windows XP before they start to support them for Windows 7. "It's just traditionally how app vendors have reacted to the release of a new OS, going all the way back to Windows 98," she said.