As the others said, check your motherboard is socket AM2 and not 939.
Also, whilst removing a heat sink and fan isn't difficult it has to be done with care as you can bend / break off the pins from your existing processor which a) renders that processor useless (although sometimes you can find people able to do repairs) and b) risks damage to the socket.
Also make sure you are familiar with handling procedures and heatsink fitting procedures as a fingerprint in the wrong place or damaged TIM (I presuming you'll be using the preapplied TIM), or air between the heatsink, TIM and processor can all adversly affect thermal performance.
Finally make sure you're grounded whilst handling the processor as static can ruin a processor quite easily. I have a long length of thick copper cored speaker cable that I tie around my wrist at one end (stripped of insulation) and around a copper raditor pipe at the other (also stripped) (my heating system IS grounded), and I use this whenever I make any changes to motherboard processor or associated components.