Vista games

Hey everyone. i havent been on gmrblogs in a while, but as i come to the end of my spring break, i figured now is as good a time as any to through out a question to this community of gamers. so anyways, i was wondering about vista today, and what it means for those of us who dont have the money to upgrade to a system that will run DX10 capable games. I am really looking forward to Spore and Unreal Tournament 2007 (now called unreal tournament 3?), but will those games run on a windows xp, DX9 pc? or will those that are still holding out on vista have to suffer a lack of these fantastic titles?