Windows Vista will be slow to overtake its existing counterpart, the research firm Gartner said as part of a new forecast. Although Microsoft has been conducting a massive campaign to promote its first new home OS release in over five years, only a small portion of the computer market will actually adopt Vista as an operating system in 2007, with 12.3 percent of the year's worldwide marketshare, leaving 77.1 percent of the market to Windows XP. Almost all of these buyers will come about through systems preloaded with the OS, Gartner says, suggesting that few buyers will consciously choose to buy Vista separately from a new computer. Vista is not predicted to surpass its predecessor until 2009, when slightly over half of the market is likely to have switched at 55.4 percent share.

None of Microsoft's competitors are likely to claim any of the existing XP share, according to Gartner. In spite of XP's increasing age, Mac share is predicted to stay largely flat at 2.9 percent. Linux too would remain small at 4.1 percent. However, the analyst firm added that the seemingly idle Mac share would come through neutralizing at least some of Apple's advantages, rather than any perceived inferiority.

"[Vista's] consumer features are just catching up to Apple OS X and iLife," Gartner said.