Him hit the spot. Raptors really are unnecessary unless your crazed about fast game loading and OS loading. The difference is quite noticeable, but really not ridiculously fast.
If you aren't getting a raptor, look into getting a Seagate Barracuda
, preferably with NCQ (Native Command Queuing). They are some of the fastest/most quiet 7200RPM drives out there, and NCQ speeds up their requests a good bit.
A RAID 0 is be a good setup as an alternative to the raptor. The only problem with RAID 0 is that it can crap out your storage in a heartbeat. Most people usually don't have problems though.