To give more information...
I have an old thinkpad, 300mhz, usb 1.1, win 98se.
The idea I have does include the use software on the laptop to make the xbox belive it isn't connected to a laptop (or PC), but connected to a memory card.
While I know this is hard due to the fact that the xbox attempts to format any recognized memory card to fatx. I was hoping to be able to mount a fatx memory card image to the usb.
If this is just too extreamly crazy or unable to be done

.... Please tell me.
Thanks for your time.