Boy, those game developers will surely be cutting their own throats then. What's Vista's present market penetration now, a year since first release? Maybe 5% of the computers. And unlike with XP, you don't see many people upgrading to it on their present systems much becuase (A) XP works just fine for them, which wasn't the case so much when XP was replacing that dreadful WinMe and (B) The hardware requirements of Vista seem to be much steeper for a computer than XP was back in it's first year of introduction. Hopefully some bright programmers will be able to port DX10 to XP unofficially.

BTW, I do have Vista and while it's workable I rather the performance I get out of XP on the same system (my laptop).