Instructions
Turn on the Xbox and go to Windows Media Center under My Xbox.
Click on "Make Connection" and write down the eight-digit number that appears on the screen.
Open the Windows Media Center on your PC. If there is an icon on your desktop simply click on it, or go to the Start menu and find it under All Programs.
Go to the Task button and click on "Add Media Extender."
Click "Continue" in Add Media Extender; which will prompt you to enter the eight-digit number copied from the Xbox. Enter the number and click "Next."
Wait for the computer to connect to the Xbox. It may prompt a reboot of the Xbox.