I rather like this site's description of RAID. No nonsense, no frills, just the basic facts of what it is and then some suggested uses.
With a RAID-0 setup, you have an increased chance of losing data compared to if you just used 1 drive, because with RAID-0, if any drive in the array goes you lose everything.
Personally I think that Raptors cost far too much for only a little performance benefit, so if you want value for money, the Seagate Barracudas are pretty good performers and so is the Maxtor DiamondMax range.
red-wax
AMD Athlon 64 3200+ | ASUS K8N-E Deluxe | G.Skill ZX 2*1024 PC3200 2-3-2-5
Gainward GeForce 7800 GS+ 512 | Seasonic S12 600W | Creative X-Fi Fatal1ty
160GB Seagate Barracuda 7200.7 | 4 * 150GB WD Raptor X in RAID-0
blue-wax
AMD Athlon XP 3200+ | DFI LanParty NFII Ultra B | Geil Ultra Platinum 2*512 PC4200
MSI GeForce FX 5200 128 | Enermax Noisetaker 470W | HighPoint RocketRAID 1820A
40GB Maxtor DiamondMax Plus 8 | 8 * 300GB Maxtor MaXLine III in RAID-5, 1.91TiB storage