I compared the 640 GB link Trotter gave and my drive, and the difference (other than $5) is the cache is 32MB for the Black. Also it comes with a 5-yr warranty, so you are better to go with that one (the 640 GB Black).
Western Digital drives seem to last forever... I've had a WD800EB from like 8 years ago, and it's still running. I mainly use it as data storage, if that tells you how much I trust it.