Supports any 2.5" IDE/PATA hard drive (no capacity limit).
That is from their site, I would assume that 20gb would work fine, capacity shouldn't make a difference in most things, it doesnt make sense to me
My guess is 5400rpm drive, that seems to be fairly conventional for an external 2.5" portable usb harddrive, so I imagine these would be similar. I doubt they are 7200rpm or 4200rpm but they could be.
I have a pair of the original Colorspace units. There's a blurb somewhere in their FAQs that there's very little benefit to 5400rpm over 4200rpm except shortened battery life, and no benefit at all to 7200 rpm. Those are the three common drive speeds. The limiting factor is the speed coming off the card reader, apparently 4200 is enough to keep up. so don't sweat the drive RPM.
I'm sure a 20GB drive would work. I use 250Gs in mine though! Just got back from four months roughing it around Indonesia and Malaysia, and filled 168GB.
