First rule of using computers = always backup your files for WHEN your HD fails...it is not a question of IF ... sometime it WILL.

Two hard-drives are recommended and never let either one get more than 50% full - since data is stored on the outside edges first the responce slows substantially as it gets full.

The main disk is for programs and opperations - the second drive contains a mirror of the first drive's setup and programs and is for data storage.