If you want better performance, you need a drive structre that is notably faster. Your options:
- A faster HD: A 10,000RPM WD Raptor, 15krpm SAS drive, Solid State or RAM drive.
- RAID0 on two drives for your OS*
- RAID1 on two drives for your data
Fast HDs mechanical are not very expensive but they are small (but this doesn't matter because an OS and app deployment shouldn't be that large). RAID controllers that are built into the motherboard aren't very good... But they're something. If you've got the cash for a dedicated controller, it'll help.
You should never keep data you cherish on a RAID0 set-up. The risk of loss is twice as much as keeping it on one disk, and small as that risk is, it's there and it's almost completely impossible to recover from.
I'd suggest keeping your real data on RAID1. You get two copies of everything and that does speed up read performance (and slightly slow write).