Buying a USB external drive could come out quite expensive. This is what I do, and it works out great and very cheap. Go to ebay and search for External USB 2 Enclosure (comes in firewire too). It should cost you about $30 or so. Then, purchase an internal drive (very cheap compared to an external and you can usually find good deals on spoofee.com for these) and pop the internal drive in the enclosure. Viola, you have yourself a high speed external drive at a small fraction of the cost of purchasing a ready made external drive!