Introduction
From the "Dashboard," navigate to My Xbox. Choose System Settings > Network Settings > Configure Network. Navigate to the "Additional Settings" tab.
Instructions
To find your Xbox 360's hardware address, please follow the steps below.
1) From the Dashboard, navigate to My Xbox.
2) Choose System Settings and press A on the controller.
3) Choose Network Settings and press A.
4) Choose Configure Network and press A.
5) Navigate to the "Additional Settings" tab, and choose Advanced Settings.
Outcome
The hardware address for your wired network adapter will be shown at the bottom left under "Wired MAC Address".