Windows 7 or win xp for games

What kind of games do you plan on playing on it?

What model is the motherboard, btw?

1. bioshock 1 and two and gta 1 to 4, I read the system requirements just looking at the graphics and my card is compatible, it's a 7900gt/gto nvidia card 256mb
2. it's a gigabyte GA-8I915P rev 2.0

Minimum system reqs for BioShock 2 alone include 2 gigs of RAM, so unless you're planning on slapping on more of it you may find your gaming rig seriously bottlenecked.

7 is worthy when u have a DX11 video card and a DX11 game

I think if you computer have whery Low CPU, Ram, Wideo Card
Then better take Windows xp

hmmm with 512 mb ram you won't come far, i suggest you take win xp, but it's even low for that. i'd say look on e-bay for some cheap ram.