I am thinking about updating my hardware to be able to play gears of war on my pc. I want to get an amd dual core of phenom+ an asus mobo. I want a 521mb pci E video card. I have no Idea which one. I know I can't spend more than a couple of hundred $s on the card. Then a couple gig of memory. can I get away with the dual core? Maybe toward the upper end? Also what is SLI I noticed that on the ASUS board I was looking at?