I recommend against a 1TB drive. Unless you have a very specific need for exactly 1 TB, you're much better off with a 0.75TB drive. The 1TB externals are all 2 drives joined together to form one large volume, giving you twice the chance of a drive failure. The controller used to join them may also become faulty, corrupting your data.
I'd go with a 750GB Seagate drive and a USB2/FW400 external enclosure.