>> here we're going to pretend. heads cbs tails, cbs number 9. >> letterman did place a call to johnny carson asking for his advice. johnny said, if it was me, i would leave. and i think that advice was really the linchpin. letterman always took johnny's advice. >> the late night wars are about to begin in ernest on american television. david letterman is now headed for cbs. >> cbs had lured him over with a salary more than four times that of leno, and given him what he really wanted, the 11:30 time slot. now as dave and jay prepare to go head to head, one thing is clear. late night tv will never be quite the same. >> all of a sudden, there's a talk show war. >> start up your remote controls. the late night race is about to begin. >> on monday, david letterman's new show debuts here on cbs followed a week later by chevy chase on fox. and a week after that by conan