Hmm cant help there. I sheepishly must admit that i am on my second MBP and have been using them for years without ever installing an AV program. I spend 95% of my time on the web and use torrents etc. and have never had a problem (touch wood). I know that there are viruses out there that will hit a mac but they are very few and far between. I have always had a AV program on my 'to do' list but i have never felt an urgent need to get to it.
I know you said you don't want a freebie version but I am using Sophos free version and it's nice and unobtrusive. They most likely have a paid package that improves and expands on the AV suite that might be suitable for you.
