0. harware firewall (sorry, forgot about that one)
1. zonealarm and zonealarm pro on two clients
2. norton on another client
3. kerio on the gateway server (as za wastes memory in the long run, does do continuous disk writes (stupid log feature) and screws up on some agent software)
4. ez-trust antivirus on most machines, but...
5. avg on one and norton on another
6. spybot (incl. teatimer on the gateway server)
7. adaware to round it all (i just love spybot)
8. syfiwa to watch for certain events (something a friend of mine is working on, it's a little tool that watches certain system files, does crc checks, and looks for changes)
have been clean now for a pretty long time