The standard XBox Operating System doesn't include support for extra USB devices other than the ones that use the XBox-exclusive customised USB protocols. It only holds driver information for the peripherals... and that's about it. However, because they are standard USB ports (and you can use your XBox controller on your PC as a joystick with the right third-party opensource drivers), if you chip your XBox, then run Linux or Windows via Linux with WiNE, you can therefore create support for any USB peripheral that Linux or Windows can run to start with - so you can (in theory, I've not tried it personally) run other USB peripherals such as keyboards, mice, and hard drives to boot. I wouldn't suggest using an external hard drive via USB - the data transfer rate is so slow that you'll be sitting tapping your fingers if you're doing any copying from disc to drive. It's much more effective to replace your original XBox hard drive with a larger one, then you can also utilise the extra capacity when you're playing XBox games (for savegames, custom in-game audio that you've loaded onto the XBox from your Audio CDs, etc)... There are many XBox sites that include FAQs on how to do these sorts of things, and many include forums populated by experts on these subjects. I suggest that you hit up Google and search for XBox Modification Guides. I only provide the starter information :) Hope it helps you get on your way though. Happy modifying.