Good advice there Hamrad. I use Spyware Blaster and Spybot weekly on my machine. Besides having my Norton Anti-virus set to automatically run every week, I also manually prompt it whenever I think of it just to make sure it's up to date.
I just spent 9 hours (!!) fixing my son's computer. He let his Norton Antivirus expire and he was infected with 7 viruses and 2 worms. Norton's "800" customer service is located in INDIA and they really are of no help as their accents are too heavy to understand even though they speak english.
Firetrucker's wife advice of a pop-up blocker is excellent also. Pop-ups can drive a person C R A Z Y.