Boot and Rescue CDs.

If you are involved in IT repair either for your business or just for casual purposes (family and friends). One of your most useful tools can be a bootable CD. Bootable CDs can either be live versions of an operating system (Linux) or a Rescue CD (e.g. AVG rescue )

A live CD can can be used to test to operation of various unresponsive items of a PC such as mouse, keyboard, monitor or simply to experiment with a new operating system.

A Rescue CD can boot a malware infected system, scan, remove viruses, malware, spyware, copy and delete files, modify partitions and a whole range of system tasks.

All the items listed below were free at the time of publication (or possibly can be purchased from the respective companies for a nominal fee.)

List

AVG Rescue CD: http://www.avg.com/us-en/avg-rescue-cd-download

BitDefender Rescue CD: http://download.bitdefender.com/rescue_cd/bitdefender-rescue-cd.iso

F-Secure Rescue CD: http://www.f-secure.com/en_EMEA-Labs/security-threats/tools/rescue-cd

Kaspersky Rescue CD: ftp://rescuedisk.kaspersky-labs.com/rescuedisk/

Ubuntu (desktop)http://www.ubuntu.com/download/ubuntu/download

This is not a complete list and new information will be added in future posts. 

Portable PC Repair Kit

Free Antivirus

Viruses will stop you from accessing Facebook or tweeting your latest activities or generally using your computer, so one of the easiest ways to protect yourself is to have antivirus, most computers are shipped with antivirus valid for a year. Most companies offer free versions of their software with advanced features for their paid versions. The links attached will provide more information.
AVG http://free.avg.com/gb-en/homepage
Avast http://www.avast.com/en-gb/index
Microsoft Security Essentials http://www.microsoft.com/security/pc-security/mse.aspx
Comodo Antivirus http://antivirus.comodo.com/