I've had a couple encounters with this trojan.
What it does is when you boot the computer or start your internet browser, it tries to connect to a site and download a virus or some other kind of malware into your system and then it activates it. There are a LOT of different versions of it out there.
A good updated virus scanner with a firewall should prevent it from working.
Just to be on the safe side, boot the computer into safe mode and then do a FULL scan of ALL FILES including archive files just to make sure you killed it.
Also, Keeping your windows updated is a good way to prevent some versions of this program from working as well.
http://vil.nai.com/vil/content/v_139961.htm
http://vil.nai.com/vil/content/v_142604.htm
http://vil.nai.com/vil/content/v_143623.htm
These are just some of the versions. It depends on what version he had in there.