I ditto the Seagate rec -- Just got two, as a matter of fact. I put one IN my computer (went from 20 GB to 120 -- it's been great!) and the other I put in an enclosure I purchased from Other World Computing. I'm sure I could have gotten a cheaper enclosure, but I liked the specs of the OWC one. (Plus, while I did do some price checking, I didn't use that particular web site -- but I will next time for tech stuff.)
Seagate's warranties are excellent. You can't beat a 5-year warranty. Plus, a lot of the Seagates come with back-up software. So you can even get a backup strategy going.