.  http://www.avast.com/free-antivirus-download Download AVG  here . http://free.avg.com/ww-en/download-avg-anti-virus-free Second you will need a firewall to prevent persons or applications from accessing your computer without authorization. The best free firewall  software is ZoneAlarm . To download it click here . What I would also encourage is for you to install McAfeeAdvisor, also free, this "