The way I transferred rosters to the original XBox was by a PC to Controller female USB cable for the XBOX and used a compatible flash drive to format it as a memory card. Than I used the hacked action replay program to transfer from the PC to the flash drive. From there I put the flash drive in the USB female to XBox controller port and transferred from there.
Hey with one of those female USB to Xbox controller adapters, could you use a 360 controller (wired obviously) on the original Xbox? I would be very excited. The controller is the main reason I would like a 360.