Asking for power could be a gamble, if they've reset the default power profile to go ahead and power down unused devices even when off of battery power. Connecting to the network is a sure thing.

I explored getting the MAC addresses from the registry, but that can be easily spoofed. Getting the permanent MAC address via IOCTL directly from the driver is harder to mess with. At least I think...

I kind-of agree with you. It's more of a windows problem that I'm trying to solve via some perl code. I'm hoping I can de-select the "allow power saving" in the device driver for the user temporarily, get the MAC address, then set it back again.