Another great find is Spy Sweeper. It actually monitors your browser and warns you of things trying to access your computer.
I've loaded it on my two machines, plus I used it plus toolbar cop and BHODemon 2.0 to find some pretty nasty stuff on a customer's machine.
Just to give you a scenario they had "The Searchmall" imbedded into their IE so that whenever they click on their IE search button it would only let you search through "The Searchmall" and then it would load about 10-20 advertisements as well. It was a booger but I finally got him all clean. Ultimately it turned out to be a BHO that couldn't be removed except through the toolbar cop.
A word of caution though....when using the toolbar cop, don't start deleting every BHO you see in this program. Some toolbar/BHO objects are necessary to run IE. The &Adress, &Links, &Radio toolbars I have left on mine for sure. The others I have are things like Acroreader and Novell (my environment) so I leave those on there. Things that give a description of Error - chances are you will be able to disable or delete without worry.
At home I use Google for a popup blocker and I'm going to be adding Spy Sweeper to my repitoire!!
Hope this helps!