The best anti-virus software is the one that works on your machine!
Believe it or not there are people out there that like Norton.
There have been several posts about this same subject. Down a search in the forums.
Just about every AV software either has a free version or a trial version. You need to find one that you feel comfortable with and works for you.
I use the free version of AVG, it works for me. You could try Major Geeks. Great site for getting links for software. Try it, you should find a load of AV software there.