Hi Photoz
I fix, repair, and sell PC's for a living. Without a second of hesitation I don't recommend the Norton or McAffee antivirus programs. They are horrible examples of bloatware.
I second (or third?) the AVG antivirus recommendation. Its 100% free for home users, catches just as many bugs as anything else, doesn't hog resources or conflict with other programs. You can download it here:
AVG Free
Make sure you completely uninstall all Norton components BEFORE you install AVG, or you will have a real mess on your hands.
Another great free program is Spybot. It complements AVG nicely as an anti spyware program. You can download it here:
Spybot
Use it to scan your system every month or so.
If you are using a router or are on dial up, you probably don't need a firewall program.
Hope that helps
Ash