Replacing Heatsink

I am going to replace my heatsink for my P4 478 pin. Can someone tell me how to go about doing this?

 

First question, why are you replacing it? Are you seeing problems with the processor overheating? Replacing it is no problem, but if you do not do it right the first time, you end up hosing up the machine by causing overheating.

 

Besides being careful & use some good Thermal paste, Here's some info:
http://support.intel.com/support/processors/pentium4/sb/CS-007989.htm

 

I am gonna replace it because the Heatsink fan is making a buzzing sound on start up. And I looked at the heatsink fan and it doesn't have screws so it doesn't look like I can replace it.