I've heard good things about some of the Lacie drives if you're looking for a boxed solution, but I'm rather partial to buying the enclosure and drive seperately. Reason being, you can pick the enclosure look/features that you want, get any sized drive you could want, and spend less than buying a boxed external.
I have
this enclosure from Macally, partnered with a 200gig Maxtor (meh) drive and I'm very happy with it. It looks good (aluminum colored with a blue led) and hasn't caused me any problems. The Maxtor is a little loud, but it was really cheap, so it's worth it IMHO.