DO NOT USE A SHIM! these things are bad, they will raise your cpu temps if it is made out of a metal. You need a heatresistent metal for thim to really work. Just be careful installing the hsf, especially the globalwins and gorbs. But a shim is a waste of money and hurts cooling.
When I installed a shim on my first Duron, it actually led to me cracking the core, since it wasn't quite perfect(in the fit department). This led to temps very close to the ambient air. I no longer use a shim, and I haven't had a problem at all.
seem to be some different opinions. . .oh well, i probably should go ahead and buy one for my tbird. if there is in increase in heat i'll take it off. i really dont want to take any chances. are the all the same?