The Seagate 500gb drives had me very paranoid. I really love Seagate and have one of their 300gb drives, but the 500gb ones have an unusually high rate of sudden death (this is judging from Newegg reviews, which even mention specific serial numbers to avoid).
I played it cool and got a WD for the same price.
Anyway, I decided to buy the drive and external kit separate. You usually can save some money doing that, and you get to choose your enclosure and what it'll support with ease. Of course, you'll probably get an OEM drive, and won't have the warranty that regular all-in-one externals boast.