western digital my passport essential 1tb
They use 2 notebook drives and put them in RAID1. We have the 7200rpm 640GB version, and it's an awesome drive, but expensive. The drive is quite compact.
It need Firewire to be bus-powered. For esata and usb, use the included power supply.
Edit: double check if it works via Firewire 400, as we use firewire 800 here. It works flawlessly with it.