Big 75 Sen. Edward M. Kennedy, Massachusetts Democrat, celebrates three-quarters of a century of living today. (If it's any consolation, women overheard in Mr. Kennedy's company of late say the senator has never looked better. What is it about him and Bill Clinton?). "Sen. Kennedy began his career setting a high standard when it comes to birthdays," fellow Massachusetts Sen. John Kerry observes in a birthday tribute to his colleague. "It was when he reached the minimum constitutional age -- 30 -- that he first came to the Senate: 1 of just 16 senators elected at such a tender age...