Saying you use Norton on a tech forum is like declaring your self a paedophile on the mother care website. They might have re-written it from the ground up but for me it will always reside next to AOL as horrible bloat ware that ****s up your computer and is difficult to remove. We use McAfee VSE at work and its horrifically bad at detecting anything.
I am with AVG at the mo, but seeing the other posts on this thread I might give MSE a go. Norton and McAfee are both major no-noes for me though.
+1 for Avast. They are pretty fast at updating their dictionary. They usually have fresh Malware identified within the week.