this has been a good topic for me as well. ive been wanting to shift over to my laptop as my main PC but have been unwilling do so until i get fast external storage. ive been doing research and Winni's comment about FireWire is deadon. if every PC you will be connecting to already has FireWire, definately go FireWire 400 as it beats USB 2.0 every time. FireWire 800 is really rockin. there are also many enclosures that are both USB and FireWire so you can get the best of both worlds. they even make really cool FireWire storage towers where you can put up to 4 HD/DVD drives. now i just need to find money (and convince the wife).
:)
:)