Okay, it's fairly simple actually.
First...IF YOU HAVE NORTON ANTI-VIRUS/SPYWARE/FIREWALL, DUMP IT IMMEDIATELY!
Norton is an inferior program that overcharges its customers and supplies false positives in order to make you believe it's working to make you believe it's working.
Here are the 3 things you can to secure your computer, and it's all free.
1) AVG Anti-Virus Free Edition
http://free.grisoft.comAVG Anti-Virus comes from Grisoft with the belief that security comes first, not profit. This program is free to home users, and is an excellent anti-virus program.
2) Spybot - Search and Destroy
http://www.spybot.comSpybot - Search and Destroy is another example of a people-come-first program. Support comes from people who donate to the program's development, and the program itself it fairly simple to use. It comes with a Resident Shield against system information changes (TeaTimer) and an Internet guardian that blocks bad downloads and sites (SDHelper).
3) Zonelabs Firewall
www.zonelabs.comFree to home users, Zonelab's Firewall (Formally Zone Alert Firewall) is a powerful firewall that offers great protection against outsider threats (Hackers).
Computer Security shouldn't cost you a dime, and it's so simple, a child could be taught to do this.