Ah, WoW loading times.
I use 2x Raptor 10krpm drives in RAID 0 for my C:, and a basic WD 320GB 7200rpm SATA drive for my D: drive. My main WoW install is on C:, and my 4 alt installs are on D:. Loading times between the drives is a difference of less than 10% - really not noticeable. I've had this Raptor-RAID 0 setup for nearly 4 years, so I've seen the results across a range of games over this time. In FPS style games, I'm usually the first one into a new map, but it's only by a second or two. If I were to spend the money again, I agree with the above - Just get one fast 150GB Raptor, and one large 7200rpm drive. There are better ways to spend the extra money. Two or more Raptors is simply unneeded heat being generated in your case, and extra cash out of your pocket. I'd rather step up a model videocard, or improve cooling performance for higher overclocking.