I have never had a problem with Western Digital and actually prefer their drives.
I have never had one of those fail on me. Whereas Seagate, one could argue that they need the 5yr warranty otherwise there would be a lot of pissed off customers. I wont go there though.
Anyhow, I would recommened that everyone buy OEM drives. The OEM Western Digital drives have a 5yr warranty like this one here
http://www.newegg.com/Product/Product.asp?Item=N82E16822144408
The only difference between OEM is and retail is that with OEM you just get the drives, nothing else. I prefer this as I like to keep boxes around. This cuts down on that. Plus, since the Mac Pro is cableless you dont need the junk it comes with anyway.
Western Digitals replacement process is great as well. They send you a new drives you send the old one back in a prepaid box. Couldnt be better, and it is fast.
So, OEM is the way to go folks you get a longer warranty and less clutter!
EDIT: I made a mistake, that drive I linked is an enterprise class drive. Thus the 5yr warranty. Typical WD OEM drives have a 3yr. Like this one
http://www.newegg.com/Product/Product.asp?Item=N82E16822136003