Now celebrating her twentieth year as the host of the world's most influential talk show, Oprah Winfrey is to television what Bach is to music, Giotto to painting, Joyce to literature. Time magazine hit the nail on the head when it recently voted her one of the world's handful of "leaders and revolutionaries." (Condoleezza Rice wrote Oprah's citation: "She has struggled with many of the challenges that we all face, and she has transformed her life.