I've heard a lot of talk about ZabaSearch. It searches publicly able government records as well as some commercial sources. A lot of people say that it violates their privacy because it's so easy to find people, so I guess it works pretty good.
Yeah, that's where I was going after proving it was hardware related I'm still concerned that your wife had two trojans on her PC though. Have you considered putting a firewall on her machine? XP SP2 has a firewall.