I recently purchased the WD4000YR for use in a non-RAID configuration. I have seen faster load times for gaming than my previous drive (western digital P-ATA 80GB, unsure which model)
So far the drive has been exceptionally fast, no errors or any problems.
I would recommend this drive to anyone, for a single hdd or RAID based system!
My PC Specs:
Asus P4P800-E Deluxe
Intel 3.0E HT
OCZ Premier Series 1x512 DDR400 DC
BFG 6600GT OC AGP8x
Hope this helps answer your questions!