To find build a good gaming computer for under 1000 dollars is hard and will not be all that great. Instead of a Sandy Bridge processor, check out the intel core i7 960. With the asus sabertooth x58 motherboard. For the gpu look into the Radeon 6800s series. (They are DX11). For the hardrive look into a 32gbs ssd, just for windows. For the main drive look for a any 7200 rpm drive. Before you decide on a power supply unit decide if you are going to crossfire or sli. For ram get 6gbs of tri channe ram.