Ok. Normally a game like Far Cry smoothes out at a gig of RAM (that's if you like to push the graphics). Additionally, when I built my latest box, I put two drives into a RAID config (cheap), set them to stripe, and zoom. Much better load times. Alot of motherboards that take SATA drives have RAID-0 support built in as well. Basically, those are the two "bottlenecks" I find most people come across when they like to game (as they usually have a good vid card and processor).
Yea, I was to lazy to bother with RAID. Invested more time and $ into audio/video (audigy 2zs with gigaworks 750 and a 1024 x 768 projector)..