"traditional" AV, no matter which security suite you own, are constantly missing major risks all the time. A-squared has a paid "anti-malware" security suite that is is better, in my opinion, than some of the big boys. I've been fighting malware for over a decade... and at some point I always abandon one AV for the next best thing. SuperAntiSpyware killed some serious malware infections when AVG, AVAST, and the rest thought the computer was fine. Malware is malware to me whether its a virus, spyware, adware or a root kit. I would rather manually run A-squared or Malwarebyte once a week than to have 19 services installed lol.
As far as firewalls... I've had almost all of them installed at some point or another... back in the old says I was a zonealarm fan... but now that I run Vista 64 and 7 Ultimate 64 my choices of free firewalls are limited. Now that you mention Norton just bought PC Tools firewall I just got a splitting headache :(