Antivirus

Download Microsoft Security Essential antivirus from this link 
http://www.microsoft.com/en-us/download/details.aspx?id=5201

Download AVG antivirus from this link 
http://www.avg.com/ww-en/internet-security

Download Avest antivirus from this link 
http://www.avast.com/index

Download Avira antivirus from this link  
http://www.avira.com/en/avira-free-antivirus