I have a
Toshiba HDDR320E03X and have been very satisfied with it. It is 320 GB, 5400 rpm, 8MB cache. It only uses one USB 2.0 port for power and is extremely quiet. For some reason the actual power consumption does not show up, but it works with my 500 mA USB ports (fortunately my laptop also has two 1A USB ports). It may be more than you want to spend on a drive, but I thought I would recommend it anyways.