Most games that are compatible with XP should be with Vista. The only difference might be how they utilize the new directX 10. I know I had the Release candidate version of vista and all my xp games worked with vista. However some of the older games may not work as well. Also, you might want to check your machines graphics hardware. To run vista fully with all of the GUI functions requires a pretty hefty machine. If you have a lower end card then Vista itself might be using all of the hardware's resources and not allowing any for the game(especially the more intenense ones). My machine has an ATI radeon 256 MB card and it does well. Of course this card is in the mediocre range but it does ok.