Dead simple way:

1. Download VFP2C32 from http://vfpx.codeplex.com/. It's a wrapper around the API Library.
2. Run this code

SET LIBRARY TO VFP2C32
INITVFP2C32(0xFFFFFFFF)
aIPAddresses('aIPs')
? IP2MacAddress(aIPs[1]) && Or whichever IP address you want from the list of network adapters