BE VERY CAREFUL! YOU COULD BE FRYING YOUR PROCESSOR !!!!
There is heat conducting thermal tape between the heat sync and processor to make sure the heat from the processor is transferred to the heat sync.
Without it, your processor will not cool properly and you could fry it very very quickly.
Thermal tape is available at Comp USA. However, if you want to go a better route, get thermal paste, which is a bit harder to apply but conducts better.
There's quite a bit of info on the stuff in this thread: http://www.powerbookmedic.com/forum/viewtopic.php?t=131
It's about a processor upgrade, but the idea is the same.