Peter, you've got to be really careful when you're downloading zip files. Lots of them contain malware. Really, I'd avoid them if you can. Please read this thread
http://www.gnutellaforums.com/showth...threadid=41432

It has a lot of helpful advice & tips on what to avoid. It's good that your AV seems to catch the infected files. It's always a good move to scan a file before opening it