Not a PC gamer yet I have like 40 games on Steam thanks to the humble bundles and some compulsive steam sale purchases... I've stumbled across a PC with an AMD Athlon II x2 250 processor and 2GB of DDR3 which I can probably bump up to 4GB by pulling memory out of one of the other PCs I have here. I'm wondering if it'd be worth it to grab a gpu (and which one) for some low-medium setting gaming. Not looking to make too big an investment as any AAA games will get played on my 360...and the PC was free. Just want to be able to play some of these humble bundle games (THQ, Alan Wake, and Deep Silver bundles) and maybe some Left 4 Dead.