Windows XP comes with the Getmac command-line tool, which you can use to quickly ascertain the physical or media access control (MAC) address assigned to a network interface adapter in a local or remote computer. Knowing the MAC address comes in handy for a number of troubleshooting operations.
Another XP command-line tool that can provide you with remote MAC addresses is Address Resolution Protocol (ARP). When used with the -a parameter, it displays the ARP cache, which stores the IP addresses and MAC addresses of the computers that most recently accessed the system.
To use it, enter the following at the command line:
Arp - a
You can even populate the ARP cache with remote MAC addresses by first pinging the remote system. Once the ping operation is complete, type Arp -a, and you'll see the MAC address of the system that you just pinged.