Actually the system Tech Savvy posted is pretty good for less than $500. Your budget is pretty limited but a 6850 should be able to BF3 at low-medium systems at the lower resolutions, but I doubt it'll play the game that well at the higher resolutions. If your budget was higher you'd be able to build a better performing system. Unless you already have a copy of Windows, that's going to eat $100 out of your budget like somebody else already said.