If you have an eSATA port on your machine (which will permit uploads and downloads that are about 6x faster than that of a USB 2.0) then you can find eSATA external hard drives out on the Web for between about $100 to $150 that are 1 TB, 7200 rpm, and with a 32 Mb cache. I'm in the process of narrowing down to a choice of one of these myself at the moment. These DO require an ac plug so that eliminates the problem of a lack of power but it's not as portable as the USB powered drives.

cchallum