I used to have Norton AntiVirus for Mac OS X, but then deleted the app when the license expired.
I think it is a totally useless app, and unless things have changed, here's why:
Norton only scans disks - not emails... so, what is the point?
Everytime I inserted a CD, DVD, or my iPod, Norton would scan those disks. I don't need Norton to scan those disks. Now, I am not saying that there is not a feature to disable the scanning of those disks, but what about emails?
Norton does not scan emails. Period.
Don't waste your money.