Keita Iida has admitted that it would have been better if Microsoft had released DirectX 10 on Windows XP rather than forcing users to Vista first.
Speaking to IGN, Iida admitted it was a bit difficult to force people to upgrade to Vista so that they can benefit from DirectX 10. He said that it's in our (Nvidia's) best interest as the only provider of that solution to have DirectX 10 software as early as possible. If Microsoft had made DX10 available on XP, this would've facilitated the development and adoption of DX10 features much faster.
Iiada said the DX10 user base would have been much higher because people with Geforce 8800s who have XP could already have DX10 available to them.
However he said the underlying kernel of the operating system and the code of Vista is a clean-break from XP. The old Windows legacy code slowed the progress of DX10 development and it slowed the user base.
He said that in the long run, it will not have much impact. We ask Mr Iida and his boss MR. Taylor where are the DirectX 10 games then?