I've got a couple of WD Raptors in a RAID 0 array and I've never heard anything like what you've just described. I'd be a little worried if I were you. At least they come with a 5 yr warranty. Maybe you should think of bringing it back to where you got it from.
"Tiger Woods doesn't win every day. We don't deny that ATI has a wonderful product and it took the performance lead from us. But if they think they're going to hold onto it, they're smoking something hallucinogenic.", <A HREF="http://www.bayarea.com/mld/mercurynews/business/5093187.htm" target="_new">Jen-Hsun Huang, NVIDIA Corporation, February 2003</A>