yeah i would stick with x86 xp for now... I am allmost 100% sure the drivers on win 7 are poor because I installed win 7 on my old computer and got about 20fps in tf2 with all settings on low when running everything on high on xp was just peachy with like 40fpsish 
but i just got a new computer with vista installed and my xp cd died so im just going to live with windows 7 rc for a while
but i just got a new computer with vista installed and my xp cd died so im just going to live with windows 7 rc for a while