Originally Posted by
DemonlockMG
Some good options would be to buy 2x WD Raptor Drives and RAID0 them.
You could also buy a Solid State drive which is even faster, but you are limited on the overall size of the drive unless you have some serious cash to throw at some of the larger SSD's.
But as these guys said, you are pretty much hitting the ceiling on your read/write speeds of your hdd. You'd see a marginal improvement just by switching to an entirely separate 7200rpm drive, but the above options will give you much better performance.