The Inquirer says it shouldn't be to hard for Microsoft to release DirectX 10 for Windows XP:
It was an honest technical reason why you could not backport DX10 to XP without a major rip and replace operation. Microsoft wasn't going to bend on this one at all.
Then something odd happened. Nvidia had about as much success implementing this required feature as it did with it Me II drivers, that is to say, none. It couldn't do it, but it was required for DX10. What's an arm twisting Vole to do? Backpedal obviously.
So, MS threw NV a life preserver and made GPU memory virtualisation completely optional. ATI, which had implemented a dandy memory virtualisation scheme got screwed, or at least got what everyone who partners with MS got. Oh wait, I said that.
In any case, in doing this, MS removed the only impediment to backporting DX10 to XP, it is now, and has been for quite a while, completely possible. MS is screwing its customers to force an upgrade and you are a pawn in their revenue generation scheme.
Charlie Demerjian from The Inq ends the article with a snip of advice: upgrade from WinXP to Ubuntu and buy a Wii. lol