Some people seem to think its spyware (I'm not so sure as I don't see what use spyware would have for adding another adapter). Either way why not download adaware and spybot search & destroy and just make sure ?
Also, is the network
known to you ? Or does it just seem arbitrary.
Last thing, get ethereal (
). See if that adapter shows up in the adapters list and then sniff on it.. since it doesnt have an IP address it should not be able to send / recieve anything.
The only things I can think of are that it belongs to some sniffer (you don't need an IP to go into promiscuous mode) or some program that needs a 'broadcast node' ?!?