I tried Pest Patrol from a free sample CD that came on a PC Magazine, probably over a year ago.
I didn't like PP, it seemed to give a lot of what I consider false alarms, maybe it could have been a bit of difference of perception as to what justifys calling something a virus/spyware, maybe PP designers were overly cautious compared to my views ?

I was annoyed that when I tried to uninstall PP it didn't go cleanly. Don't know if this was due to something I failed to do right or a deliberate strategy of PP. Anyway, in the end I had to go through the Registry with regedit and manually remove all references to PP, myself.