 The purpose of this study is to compare the two methods of clamping to see if one way is better than the other, and to determine whether patients who undergo reduced manipulation of the aorta have fewer microemboli delivered to the brain during CABG surgery and have a lower incidence of neurobehavioral problems following surgery. Microemboli are tiny fat particles that enter the bloodstream during surgery, circulate to the brain, and block tiny blood vessels, causing brain deficits. 