Copper, Copper..and um...Copper...No seriously, you'll probably hear a lot of reccomendations here. I'm gonna try to run a 750 Duron on a GlobalWin FOP38...they're really cheap right now.
I'm using a CAK38 w/ is a solid copper unit on my 850 PIII and it works like a charm but were talking about apples to oranges w/ comparing a PIII 850 to a Duron 850 when it comes to heat output.
Someone will surely chime up sooner or later...Good Luck.