As a note to everyone who owns a 4XXX model. You don't have to remove the heat sink to clean it. My heatsink was so firmly attached to the processor that I decided to take other measures to clean it.
All you need is a flashlight, a can of air, and two hair pins (thin tweasers would have been better).
1. Turn the intact laptop upside down and shine the flashlight into the rear exhaust vent. You should be able to see the dust, hair, food, whatever by looking back at the light from the large fan air intake on the bottom of the computer.
2. Stick the tube from the air can into the heat sink slots one by one, and blow the dust back into the fan housing. It's best to turn the computer right side up and hang the fan intake over the side of a table for this. Let gravity take hold of the small dust particles.
3. Now, you should see a large dust ball or two stuck around the fan on the bottom of the computer. The dust balls are pretty strong usually. So, you can actually pull them through the tiny intake vent holes covering the fan. I used two bent hair pins for this, but a thin set of tweasers would work better. Stick both of the hair pins through the same hole in the intake cover, pinch the dust ball, and pull through the hole gently.
4. Use the can of air to continue blowing out the small dust particles from both sides (heat exaust and fan intake).
My computer used to idle with the processor at 65 C and the fan constantly running. Now the fan can take the processor from 59 C to 50 C in less than a minute, and it never goes above 60 C.