BAD TO THE BONE -- Some early tough guy and tough gal performances from Harvey Keitel, Debra Winger and Leonard Nimoy. YESTERDAY'S NEWS -- TV star David Letterman is shown as a newscaster on Mary. STAR ANECDOTES -- After Betty White and Marie Osmond recall their first television appearances, comedian Drew Carey takes a look back at his 1988 debut on Star Search. GUESS WHO? -- Audience members are asked to identify Loni Anderson and a young Dennis Hopper. AS THE STAR TURNS -- Meg Ryan's 1982 appearance on As The World Turns. SONG & DANCE -- This segment features a look at Academy Award winner Woody Allen on The Kraft Summer Music Hall in 1965. BEFORE THEY WERE STARS YEARBOOK -- Featuring high school photos of Michael Keaton, Rosie O'Donnell and singer Garth Brooks. SONG OF THE WEEK -- Actress Mare Winningham is shown in 1977 on The Gong Show. BEFORE THEY WERE STARS COMEDY CLUB -- A trio of clips looking at the early stand-up careers of comics Tim Allen, Billy Crystal and Kevin Nealon. A