I built a system using a 939 Opteron 148 (single core, 2.2 ghz) cpu and 2 gb of RAM (4 x 512mb) to give to a friend of mine so he can play TF2. First I tried Windows 7, but I kept getting a lot of lock ups and blue screens. So I decided to install Windows Vista. Vista has been more stable with this ASUS motherboard, but cpu usage is crazy. Doing nothing it will jump around and even reach 100% at times. While playing TF2 I can tell it's just not as smooth as what it should be. The video card is an x1800xt. This same system has been used to play TF2 in the past when my son had it. But it was using XP then. Is there any reason why Vista is doing this? I have Vista installed on my own PC, and I don't have this problem. Of course, my cpu is a quad core Phenom. Is the cpu usage so high because the Opteron is only single core? The Vista install was a clean install, and it is pretty bare. Only things installed are Catalyst Control Center, Steam, and Team Fortress 2.