Avast is likely the best AV program on the market, and since its free for personal use, it isn't even on the "market!"
Norton is just and AVG is OK, but Avast is MUCH better. I'm always ready to update spyware.
Also, there's a program called CleanCache that cleans out IE files like nothing else. Even if you now run Firefox or another browser, chances are your termporary internet file folder is clogged and CC will clean it out. Its also free.