I have been backing up my C drive with DVD+RW disks, and am considering an 80 GB external HD. I am ignorant about imaging (backing up) the whole pc hard drive on an external drive, so if I could get some advice as to what to buy, I can learn the rest. I see mobile external drives, but they seem to be for laptops. The external HDs available in stores by me are all too big. All I need is 80GB. Thanks for any input in advance.