http://www.free-av.com/en/trialpay_download/1/avira_antivir_personal__free_antivirus.html
2. Avast Antivirus ( Home Edition )
http://www.avast.com/eng/download-avast-home.html
3. Avg Antivirus ( Free Edition )
http://free.avg.com/gb-en/download-avg-anti-virus-free