I just installed (July 17-04) Avast 4 Home and was very disappointed to find that it did not catch IRC/Backdoor worms/trojans - Protoride, RADO or MsUpdate.exe and WinUpdate.exe, Seteada.A. Even when I forced Avast to scan just those files - it found nothing. Needless to say, these were/are rather potent viruses which Norton, McAfee (even !) and AVG found immediately.
Not too impressed at this stage with Avast - although it looks nice 
Matthew