Get a seagate drive - they've never let me down. Maxtor haven't either, but they're kinda 'cheap'. Western Digital have let me down before, and wouldn't recommend them.

Don't get one big drive - hard disks are built to a far lower standard compared to how well they were made 20 years ago - get two of half the capacity you want - this way, if one dies, you'll still (potentially) have half your data in tact. Don't buy two at once from the same supplier, as if the batch they're both from is faulty, they'll both die at once if the unthinkable happens.

Or get two bare drives and stick them in a Netgear SC101.