Follow the appropriate instructions to determine your computer's physical address.
Microsoft Windows XP
1. Click the Start button.
2. Select Run. The Run dialog displays.
3. In the Open: field, enter cmd, then click OK. The system 32 cmd dialog displays.
4. Enter ipconfig /all (notice the space) and press Enter on your keyboard. The physical (hardware) address of your Ethernet card and wireless card (if you have one) display, along with other settings.
5. Write down your physical addresses.
Apple Macintosh OS X 10.4
1. Click to open the Apple menu.
2. Click System Preferences.
3. Click the Network icon.
4. Under "Show" select "Built-in Ethernet"
5. Click the "Ethernet" tab
6. The MAC address should be listed next to "Ethernet ID:".
7. To determine the physical address of your wireless card, select "Show: AirPort", click the "Airport" tab, then the physical address of the wireless card should be listed next to "AirPort ID:".
8. Write down the physical (MAC) addresses.