R help - Oct 2003 - Power computation

Hello,

Thanks everyone who replied to my earlier Q.

I ran into a problem. I am analysng multicenter clinical trials. The model is

Y=treatment + center + treatment*center. I have the effect sizes and the 
patient distributions for each scenario in the simulation.

Can someone tell me how to compute the power in this case? May be by using a 
F-test or something like that.

Thank you very much.

Krishna S P