what thermal compound you get is your preference (stuff mentioned by patrick is really good any of those will work wonderfully) what matters is HOW you apply the thermal paste. for a closed look heat-sink (well all heat-sinks in general) the best method that I use (and considered the best by hardware secrets and toms hardware) is to apply the thermal paste as a small dot about the size of a BB pellet in the dead center of the processor. good luck with the remount