No RAID-0 needed for desktops
AnandTech: Western Digital's Raptors in RAID-0: Are two drives better than one?. I was going to get a pair of 74GB 10Krpm drives in a RAID-0 to just get screaming desktop performance.
Indeed, it does look like that RAID-0 double actual disk throughput, but because a single drive also has caching and lookahead, the real world "delivered" to the application performance is only about 20% faster disk speed compared with a single drive.
Then when you take an actual overall system level performance in say Winstone or loading a game, you find it just washes out.
Defragging your hard disk is probably a bigger performance driver. So, the net, net, is get the 10K rpm drive, but you only need one and no RAID is needed.
Best use of RAID seems to me to be for RAID-1 mirroring so that it is easy to do backups.