h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

My subscription to Norton AntiVirus 2005 is due to run out on Thu 17. Subscribing for another year would cost a bit (last time was £160 from Staples, IIRC). So I've decided to try free downloadable anti-malware software. On Sunday, I downloaded and installed Grisoft's AVG Free (http://free.grisoft.com).

Today, the first problems. My ECDL tutor e-mailed me the files for another test to my Hotmail address. Hotmail blocked one file, so I asked her to try an address I use with Outlook Express. Soon, AVG's E-mail Scanner came up, but Outlook Express reported "The connection to the server has failed". I removed Norton and rebooted, and voila, Outlook Express has now fetched all the e-mails I had expected. That is, the cause was Norton and AVG coexisting. I hope this sort of thing isn't prevalent. I'd like to think I could install several anti-malware products without things ceasing to work because of combinations of programs coexisting, when it isn't clear what combinations to avoid. Will AVG be jealous of any other anti-malware program, I wonder?