Ronald Reagan became president even though he worked with chimps in B movies. Arnold Schwarzenegger played a murderous robot, and that didn't keep him from becoming governor. So can "Law & Order" actor and former Sen. Fred Thompson (R-Tenn.) become the first presidential candidate with this credit? Thompson played a white supremacist, spewing anti-Semitic comments and fondling an autographed copy of "Mein Kampf" on a television drama 19 years ago. His colleagues say that he was just an actor putting everything he had into playing the role of a charismatic racist, named Knox Pooley, in three episodes of CBS' hit...