TheMAC Addressfor your Xbox 360 is displayed on the left side of the screen in a format like12AB34CD56EF.

Select Done when youre finished.

Note: You dont have to worry about the Alternate MAC Address in most cases.

XBox 360 Basic Settings

This is only used if your Internet connection is accessed through your rig instead of a router.

Thanks to Chris Edwards for help in updating this post.

XBox 360 Additional Settings Screen

XBox 360 MAC Address Screen