If it doesn't pass one or more of WD's Datalifeguard tests, they will replace it.http://support.wdc.com/product/download.asp?groupid=810&sid=3&lang=en
Damn. I didn't see your post. I already shipped out.
I tried to make my NAS accept my drive but it failed twice and plus, it was making clicking sounds + 30 bad sectors were detected.
I hope I do get a replacement. It's my first time sending for RMA, never had a unit failed on me. $10 of shipping out of my pocket and another $5 for packaging. I hope they don't send me the same drive back and telling me it is still good when the health life dropped by 1/3.