Hmm...let me see...
The noise you describe might be normal; I don't personally own a Raptor to tell you, but since it's a 10,000 RPM drive, I would suspect it could be the motor making an abnormal noise, but not sure.
I would run WDs Lifeguard utility on the drive and see if it reports anything out of the norm, if not, then I would assume it's just overly noisey.
Athlon 64 X2 7750 Kuma @ 3360 Ghz @ 1.475V (14.5x223)
(NB: 2240, HT: 2015)
Sparkle GeForce 9800 GTX+ (755core, 1350 mem)
Onboard sound (yuck)
4GBs Mushkin DDR800 (6/6/6/18/24 @ 928mhz)
2x74GBs RAID 0
2xWD 1TB HD RAID 1
Plexter DVD Burner