Centering graphics by default in Sweave

Is there an elegant way to get Sweave to center graphics by default? 
I'd like to use \centerline{\includegraphics{}} etc. to save some 
vertical space that \begin{center} ... \end{center} uses, and I'd like 
to avoid centering with each <<fig=T>>=

Thanks
Frank

Frank E Harrell Jr   Professor and Chair           School of Medicine
                      Department of Biostatistics   Vanderbilt University