I'd recommend AVG, and I work for an ISP that has no loyalty to the product. Before you uninstall Norton you need to temper its enthusiasm, by turning it down, otherwise you just remove the handles. Norton is an evil machine who's employees are encouraged, if you were to ring them, to tell you that you must pay more money to have viruses removed and even more to have files condensed otherwise the universe will implode and it will be your fault. At least that is what they put over. They rate people on their address. If it sounds posh, they'll charge you more. Or if you sound like you don't understand computers; they'll charge you more. I have little doubt that artificial intellingence, one day, will take over the world - Believe me, someone/thing from Norton will be in charge.
Go to:
http://free.grisoft.com - these people are showing signs that they can be trusted. Hope that helps.