Hello everyone. Need some assistance here. I'm rebuilding my PC with a Phenom 9850 B.E. quad core cpu in an Antec 900 case. What heatsink do you suggest to keep it running cool? I current have a Zalman CNPS 9500 AM2 heatsink. Would it work?

I'm not sure if CNPS9500 would work. It looks like its designed for Socket 775 only. However if you've used it on your previous AM2 machine, then it would definitely work. You shouldn't be worried about replacing it.
 
But if you're looking at some moderate overclocking on the 9850 BE, then you should consider getting a better heatsink. I would personally recommend Thermalright TRUE-120 Extreme.