For the average home-user, anti-virus software is a must. A...

For the average home-user, anti-virus software is a must. A personal firewall such as Zone Alarm and running a program like HFNetcheck, which is a free download for personal users. It checks your system to see if anything needs to be patched. I'd also recommend a program such as SpyCop to periodically check for any spyware on your system.