For a good AM2 cooler, most S939s still work. I use an Arctic Cooling Freezer 64 Pro and it works pretty good. You could also get a massive Thermalright XP 120 if you want but you need a lot of room and a new cooling solution bracket. See here:
Get a good 120mm fan on that (Silverstone) and your CPU will be in temperature heaven. But for everyday use the AC F64 Pro is great, and very quiet. I think it's a little cheaper than the thermalright also, seems like mine was $25. It wouldn't hurt to get a better bracket though, mine broke (because I installed the heatsink wrong) so I had to replace it. Got the Rev. B bracket like on that site and it works great, survived a small drop even. But 939's will fit AM2's if you do not modify the bracket, it's just a little bit weaker for big heat sinks.