don't even concider using norton, it's the worst shit in the market, it may delate your system files and destroy your OS - you may lose data.
For complete security on my windows workstations I am using nod32 + avast! antiviruses and AdAware + SpyBot - Search & Destroy. As firewall I am using kerio firewall.
Anyway I am trying to use windows as less as I can. I am using Ubuntu linux on most of my company workstations and I am very fuckin happy and satisfied. No problems at all.
http://www.ubuntulinux.org/