The current driver model on the Windows XP is the limitation. One of the key points of Direct X 10 is to be the ability to have more independent objects and the current driver model on Windows XP simply won't be able to deal with it.
Direct X 10 hardware will of course run Direct X 9 games and it is also supposed to do so fast.
DirectX 10 for Windows Vista only
Posted on Friday, Jun 16 2006 @ 21:36 CEST by Thomas De Maesschalck