AMD site says the processor should be running from 55C - 70C, and 1.3v - 1.35v. To cool it down a bit more, I'd suggest using a zalman heatsink, and using arctic silver 5 as the paste. Using the stock grease they give you on the stock coolers kills temps. Really, any decently reviewed heatsink will be ok, just use good thermal paste.
I have a Thermalright Ultra-120... They also have an Xtreme model which is like $62 as apposed to the plain U120 at $48. Not worth it in my opinion but Mine cools my Core2 incredibly. It comes with a plate for the AM2 sockets as well, but i think they suggest the adapter plate for it which is extra It does not come with a fan but just get a good 1800-2200rpm 120mm fan and you are set to go. It's a beast of a cooler and almost to liquidcooling levels.