Norton USED to be good software. Unfortunately, no longer.

I now use AVG for virus protection with ZoneAlarm as a firewall and Spybot S&D (use the "Immunize" feature) & Ad-Aware for spyware protection/scanning.

But the best defence is common sense. Don't fall for phishing emails, don't download scads of free software and demos just to "try them out", don't click ANYWHERE on pop-up windows and keep everything updated.