So, I had a chance to try clamwin on a really hosed computer (my parents') and it didn't do so well. It's scan speed is quite slow and I was left with a lot of question about whether it was actually doing anything.
I uninstalled it and installed AVG free and it's done well. I'm still going to have to reload their computer, this time with firefox, MSAS and AVG. I'll have to dig around for any other good config tips.