This is my May 2006 Macbook (1.86ghz, Core Duo) that has been having some temperature issues as of late. So I ordered some Arctic Silver 5 thermal paste thinking that perhaps it suffered from the usual thermal paste overload of the 1st gen Macbooks. Upon opening I found lots of dust in the heatsink. After cleaning and applying new thermal paste, temperatures have gone from about 85c to 55c when watching youtube videos. The thermal paste was not that bad before, but I think most of the improvement has come from the dust removal. Anyway, this post is just for reference for anyone having similar problems.