I have 80GB of 250 dedicated to Windows 7 for gaming... I use it to play MW2, BF:BC2, TF2, Left4Dead 2, Halo 2, GRID, and Red Faction: Guerrilla. They all fit on the partition with 20GB to spare, although a lot more space will be taken up when BC2 comes out as I have the beta right now which is 1.5GB