Um... chemjam, the origninal xbox is also usb. It has a different jack, but it is usb. There is an adapter that will convert from the xbox usb jack to a standard usb jack. Now, as far as the 360 controller working on the xbox using this adapter I can not say as I have not tried it.
....."by chemjam - 11/23/05 10:43 AM
In reply to: Can you use a wired xbox360 controller on the original xbox? by johncpatterson
No you cannot use the new xbox 360 controller on the old xbox. The new xbox 360 is a usb device. It can however be used as a PC gamepad with proper driver download."