Whatever you choose to use, you'll need to uninstall Norton 360. (Having 2 antivirus programs, or firewalls, on your PC - even if the registration for one has expired - can lead to problems). You can't uninstall the Norton software from Add/Remove Programs. You need this tool:
http://www.symantec.com/norton/support/kb/web_ view.jsp?wv_type=public_web&docurl=20080411113 806EN&ln=en_US
(Just use the download from Step 4. You can ignore the rest of that page).
For many years, the majority of the 'regulars', here in AB's 'Technology' section, have used AVG Free as their antivirus program. If you want it, use the left-hand 'Download' button here:
http://free.avg.com/download-avg-anti-virus-fr ee-edition
However, some people have been dissatisfied with the latest version of AVG Free, resulting in them switching to Avast! Home Edition:
http://www.avast.com/eng/download-avast-home.h tml
You'll also need a decent firewall. Most people around here seem to use Zone Alarm:
http://www.zonealarm.com/store/content/catalog /products/zonealarm_free_firewall_b.jsp;jsessi onid=JbNcJiQXzOJ2kc2DkHNUMj51Wj5pwTRulO2104y2d mvjkoBve124!1454344702!-1062696904!7551!7552!N ONE
but Comodo is also popular:
http://www.personalfirewall.comodo.com/ <