I got an I/O Magic 250GB USB 2.0 HD a few months ago and so far it's worked great. USB/1394 shouldn't make much difference performance wise, but as Ham said I'd go for USB for compatibility. If given a choice I'd take one of the better HD brands like Seagate, WD, Maxtor, etc (my drive is actually Seagate, I/O Magic just makes the enclosure). I've also seen some Fantoms around for fairly cheap