yes!! is it your heat sink that is hot? Or the whole inside of the tower?.. The heat sink will generally run a bit warm. But it should not be so hot that you can't touch it, or hold it for a few secs.
If it's the CPU heatsing that is really hot, then a) make sure it isn't clogged full of dust. b) make sure the heat sink is seated correctly and that all 4 corners are where they should be. Do you have an extra exaust fan at the back of the tower taking the hot air out of the system? If not, invest... they are really cheap and very helpful.
Let me know if you still have troubles..