Just to thow in my $.02, it also helps to use some wet-dry sandpaper (600 grit, I think), and a few drops of water and dish soap to lap the heat sink to a polished surface before mating to the CPU with a very thin layer of Arctic Silver. 30 minutes of sanding will make for a well polished surface. If you can, do it with the sandpaper laid out on a flat glass surface, rough side up, and move the heat sink in circles on top of the paper while applying even pressure. You can pull those temps into the 40's with air, if you're careful and take the time.
I have too much time and too little aggravation in my life, so I built a carPC. ;)