If you don't need it, I would advise against RAID. You can get two fast drives, and load everything on there like that, keeping your data / storage seperate from your operation system. If you just outright want speed, I would suggest getting an external (PCI, PCI-X, or PCI-E; not on the mobo) controller, and hooking up two fast drives (74GB Raptors or whatever floats your boat--search for hd benchmarks, and use them), and then have another 120-250gb hd for storage...
My $.02
Tas.