Instructions
Highlight "Windows Media Center" from the "My Xbox" menu of the Xbox 360 and press the "A" button. Select "Continue" and press the "A" button to begin the setup process.
Write down the 8-digit key displayed and press the "A" button to continue with setup.
Click the "Start" icon on your PC desktop. Click "All Programs" and click the Windows Media Center icon to begin the Media Center program.
Click "Add Extender" from the "Tasks" menu on the Windows Media Center menu screen. Click "Next" to begin the extender setup process.
Type the 8-digit key you obtained from your Xbox 360 and click "Next." Allow your PC to configure the connection between your Xbox 360 and computer. Once the process is complete, click "Finish." Your Xbox 360 will now display the Windows Media Center on your television display and can be used to access the media stored on your PC.