Unfortunately the big games are like 10GB installed apiece now! On my comp, Call of Duty: World At War - 8.05GB and that's two games back. Killing me trying to buy an SSD here. If you're going to install 4 or so big games, that's conservatively 40GB. 64GB SSD won't cut it for that. I'm trying to choose between the Crucial C300 and the OCZ Vertex 2 now too, or nothing and use my current 640 WD black but get a SATA III mobo and a new SATA III SSD for less later. Cheapest I'm finding the Crucial C300 128GB is $264 at Amazon.
So a Win7 installation set up for gaming (just the base system, no games installed) is over 20GB nowadays?