Also id get trojan hunter- itl seek for trojans on your system and kill them

http://www.trojanhunter.com/

Also Antivir iv found to be a fantastic virus killer

www.free-av.com/

MOST IMPORTANTLY- get a decent firewall!!

Zone alarm is free and fantastic, the free version is totally sufficient for most needs

www.zonelabs.com/

ps- avoid Norton at all costs. Its crap, slows your system down and is only onestep removed from spyware itself. Die Norton Die!