The AVG Rescue CD is essentially a portable version of AVG Anti-Virus supplied through Linux distribution. It can be used in the form of a bootable CD or bootable USB flash drive to recover your computer when the system cannot be loaded normally, such as after an extensive or deep-rooted virus infection. In short, the AVG Rescue CD enables you to fully remove infections from an otherwise inoperable PC and render the system bootable again.
Special Note from AVG Official Site:
The AVG Rescue CD is a free-to-use product that anyone can download. This also covers any new program versions and virus database updates. If you have any other paid AVG license, you are also entitled to receive our full technical support.