This episode's headline: Soldiers Present, Soldiers Past; Sudan's Suffering; Smart Trek; Dialogue. ANCHOR: JIM LEHRER; GUESTS: PRESIDENT CLINTON; STEPHEN AMBROSE; CORRESPONDENTS: TOM BEARDEN; ELIZABETH BRACKETT; DAVID GERGEN; MARGARET WARNER; PAUL SOLMAN; PHIL PONCE; KWAME HOLMAN; TERENCE SMITH; SPENCER MICHELS; ELIZABETH FARNSWORTH