DirectX 10 is available exclusively in Windows Vista, meaning that the graphics technology is shipped as a default component of the latest Windows client and that it is not available for download from Microsoft as DirectX 9.x is. In this context, Microsoft has made Vista an integer part of the equation also containing the best performance video cards, DirectX 10 and the top gaming experiences. Windows XP users are simply left to hang... Microsoft has not developed DX10 for Windows XP, and will not implement it into XP.

Philip Taylor, Microsoft Senior Product Manager revealed that the lack of synchronization between the development process of XP and DX10 is also at the basis of Microsoft's decision not to make DirectX 10 available for Windows XP.

"Let's consider the software development lifecycle, the DX10 lifecycle, and the history of Vista. The first step taken is to create a code branch for the new OS. XP RTM'ed in August 2001. DX10 itself wasn't fully baked when the initial branch was taken. DX9.L to support Aero and desktop composition took a bit of time," Taylor explained, saying that DX10 is a direct result of the negotiations with the IHV community, negotiations that ended only towards the end of 2003.

While XP was made available in 2001, and the Longhorn reset was planed for 2004, Microsoft managed to solidify the design of DX10 only late in 2003, and release the first SDK with support for DirectX10 only in 2005.

"Given the new features in the driver model and hardware (with GPU task switching, GPU memory management and more) all of which require kernel support - hoisting a driver layer like that on XP is rewriting it to be Vista. FWIW, the MS hw developer page has the graphics logo requirements and it explicitly mentions these GPU features as being required. They are essentially hidden features that API programmers and end-users never see," Taylor said.

With DX10, Microsoft has moved to serve new customers as opposite to the existing ones. According to Taylor, Windows XP users have had a run for their money for the five years it took Microsoft to develop Vista.