Choose your pick from http://www.tomshardware.com/charts/gaming-graphics-charts-q3-2008/benchmarks,30.html.
It's up to you to decide between high-quality or mainstream.
i'm getting an asus essentio CG5275-AR003 that i will be using for gaming. but i want to get a video card for it seen as it only has an integrated card. i'm already shellin out 700 bucks for the computer so i cant spend to much on the card only 100-150. i dont know much about the subject so please help.