actually, woofgang, the car shocks because it's on rubber and Not earthed, same as a metal door handle (not earthed), the radiator is earthed, so it takes your charge and dissipates it to earth with no shock, try it for me, be bold, people have done worse in the name of science, and if any electrician/physic types reading this, please reassure woofgang that i am right :-) also techies will agree, that you need to earth yourself on radiator or water pipe etc before you ever touch inside your pc. Right, techies..