Hmm, you should be able to buy proper external hard drives where no cases are needed which can work with firewire, and USB 2.0 for example to conncet to a PC, and these aren't as expensive as you might think, but for a small one, i'm not too sure (though you could hit two birds with one stone if you were into music and wanted to store files on too, since you could buy a hard drive storage MP3 player
)