I'm building a new very fast system, mainly for gaming. I have two 500GB SATA150 hard drives that I'm thinking of re-using, but I'm not sure whether I should buy a couple of SATA300 drives instead. How much actual difference in performance do you think I'd see if I went with the SATA300 drives?
The drives I currently have are Samsung HD501LJ, 7200rpm.
I guess it depends on how hard core the gaming machine will be. If your gonna spend money on 2 4870X2's and overclock an i7 chip to 4Gz, then by all means upgrade the hard drives. However, I kept an old seagate barracuda(IDE drive) from an emachines computer for my build this summer (4Gb ram, e8400, radeon 4850), but upgraded to a samsung spinpoint f1(SATA300) this December. I can honestly say I didn't notice much of a difference between the two in games. If a game does a good job pre-loading areas into ram, and you have lots of ram, then i don't know how much a faster hard drive really helps.
On the other hand, games that load lots of stuff at once into ram should benefit more from a faster hard drive. I guess you could ask yourself if your games are jumpy how they are now. if not, then I don't see any need to upgrade right now. You could always do it later when prices fall more.