Disconnect your internet cable from the computer.
Turn off system restore because some of these critter can re-infect from your restore points. Restart in safe mode and then do a virus scan. Safe mode will prevent most of the crap from loading and disabling your anti virus or camouflaging it's self. Also if you try to install other programs to hunt down these bugs do it in safe mode.
The free version of
Zonealarm is a much better firewall than Microsoft.
Hijackthis is a great program for stopping unwanted programs from running.
