How do you install 2 nics in a notebook?
Maybe I'm reading it wrong, but didn't djhuk say his desktop MAC is already validated and he's trying to add the laptop?

edit -- he's not real clear on which computer is already validated. If it's his laptop already validated, he could have the net admin pull his laptop validation and have his desktop's MAC validated after he's added a second nic, eh?

Here's a rundown on XP's built in ICS:

http://www.practicallynetworked.com/sharing/xp_ics/