I screwdriver will do, all you do is stick it in the slot on the clip, and pull it towards the heatsink to pull it up and over the little notch. It will take some force to get it off, but it wont be that hard. You might run into problems if you have a thermal adhesive between your heatsink and core, although it seems illogical to do this with that type of CPU. Be extremely careful when doing this, as it doesn't take much to chip the core. You must keep the force of you removing the clip off of the cpu core, and you will want to keep the heatsink as parallel to the cpu as possible until you are ready to gently pull it off.
Most retail heatsinks have a gummy substance, thats alot harder to get rid of and remove than normal paste. So you might want to run the computer for a little bit before you do this, as to get it warmer and thus more pliable.
As for taking the compound off of the core...I don't know, I'd say just use a credit card very carefully, but I've never been told how to do this so I dont want to tell you the wrong way of doing it.
Good luck
