that cpu is a '939 socket' design so you are looking at for a cooler that will be compatible with this.
they are fairly old so you may be somewhat limited to what is available and may have to purchase off ebay. just get something cheap that will do the job. also check if it comes with thermal paste or compound already applied or if you have to buy your own to put on. there are numerous ways to apply it but you can look these up on youtube and watch how its done.
also make sure you clean the old thermal paste off your old cpu when you remove the dead heatsink. use 70% or higher isopropyl alcohol to wipe it off.