Antivirus sucks. Stay away from this type of software.
http://arstechnica.co.uk/security/2015/09/security-wares-like-kaspersky-av-can-make-you-more-vulnerable-to-attacks/

The security of the computer is responsible user and updated OS, browser and other softwares. BTW, some antivirus like Avast add their own SSL certificate into the OS and execute a MITM attack on HTTPS websites in order to scan the content.

AVG sends your personal information to third parties with commercial/advertising purposes.