For viruses and worms http://forum.avast.com/index.php?board=4.0
Follow instructions at the top of the board…http://forum.avast.com/index.php?topic=53253.msg451454#msg451454
To install Comodo Firewall follow these instructions
This will prevent installing the Comodo Antivirus. I am running CFW v5.12 w/D+ alongside avast free with no problems.
For CFW v5.12 here’s the link.