Microsoft users' shock about the Windows Vista announcement could undermine a more positive response to other changes in the Software Assurance licensing scheme, which was first introduced in 2001.
Microsoft has added eight new benefits to the package but confirmed that it would not alter the programme's core payment structure, despite coming under pressure from users to do so.
Some IT directors have complained about not receiving full value from Software Assurance when the introduction of upgrades has slipped.
Mark Buckley, Microsoft's licensing manager, said very few organisations have been adversely affected by the late delivery of such upgrades. He said the additions to Software Assurance reflect customer feedback about gaps in the Software Assurance model, particularly the need for better support.
The new features include a consultation service lasting between one and 10 days to help customers develop a desktop deployment plan that makes best use of new tools and technologies while minimising the total cost of ownership.
Another enhancement is the introduction of round-the-clock phone support to help resolve "business-critical outages" for all products covered by Software Assurance.
David Roberts, chief executive of the Corporate IT Forum, who in last week's Computer Weekly urged Microsoft to reduce the cost and complexity of its licensing process, said, "Microsoft should be applauded for listening and concentrating on the cost.
"However, the licensing scheme is already fairly complex and these extra benefits could make it an even more time-consuming exercise for firms to reach the right decision. And wrong decisions in the area of Software Assurance are very expensive both in money and man-hours."