The estimated start of any war in the Persian Gulf will be sometime in the second or third week of March, which, of course, is when the focus of every basketball fan is on the opening rounds of the NCAA Tournament. CBS issued word today that if the war starts at or before the tournament, they will preempt the action to provide more news coverage. In that case, the tournament would shift to either TNN, VH-1, or MTV, which, like CBS, are owned by Viacom.