well no need of exactly for insuring desktops I think, you will be just burning your system and asking for it to be paid.
I think all parts providing company give enough replacement warranty which is real good.
Warranty is a different kind of insurance and is for hardware and electronics, meaning making them, and you no paying the price wrongly. Besides I have question, what does it means if you go for full parts warranty with any company like Dell or HP for their branded systems