Hi Alan, you could try “Hijack this” from this page : http://www.spywareinfo.com/~merijn/downloads.html
About Zone-Alarm: it’s a firewall, not an antivirus-program.
You need both of them. Allthough you might not notice it, a firewall protects you in a way against certain new virii like Sasser.
So with Avast! and Zone-Alarm you’re pretty safe. 