Try hooking your computer up through a hub or something and use WireShark on your traffic. You never know on a Windows box. I've had deeply rootkitted machine

Try hooking your computer up through a hub or something and use WireShark on your traffic. You never know on a Windows box. I've had deeply rootkitted machines that didn't get picked up by any scans. In any case, I'd recommend against changing your MAC address because when you do get a hold of the network admins they may be rather disgruntled that you're violating network policy (almost any university that registers MACs prohibits MAC spoofing, otherwise you could just use the MAC of somebody that you saw on a different subnet).