A Live CD is a bootable operating system that resides on a compact disk or DVD and loads into RAM instead of from a hard drive. This can be very handy especially for data recovery when the disk you are having problems with was your operating system disk.
Generally most of our favorite Live CDs are flavors of Linux. This is great because with Linux you have an array of great free pieces of software that can be used to aid in your recovery. Try Knoppix or Ubuntu to get started! Simply download the .iso and burn the image to disk. Then drop it in your CD/DVD drive, set the machine to boot from CD and turn on the power! This frees your hard drives to allow complete access!