Instructions
Plug in the Windows Mobile device into the Xbox 360. This is done by plugging one end into the phone and the other into one of the three USB ports in the Xbox. One port is located on the back and two in the front; the two in the front are under the door next to the "Power" button.
Go to the Xbox 360 dashboard and locate "My Xbox."
Locate "Windows Media Player" and follow the instructions on the screen until the eight-digit code pops up.
Go to "Windows Media Player" on the Windows Mobile device.
Select "Tasks" and locate "Extender."
Enter the eight-digit setup code from Step 3.
Follow all instructions on the device.
Select "Finish" on the final screen on the device. The Windows Mobile device and Xbox 360 are now synced together with all media files located on the device now available on the console.