AT THE MOVIES, with ads touting that it “sets the cinema back 900 years,” Monty Python and the Holy Grail (right) goes on a theatrical crusade. IN MUSIC, Elton John’s Captain Fantastic and the Brown Dirt Cowboy debuts at No. 1 on the Billboard album chart. IN BOOKSTORES, Thomas Harris’ Black Sunday, about a plot to bomb the Super Bowl, is a New York Times best-seller. AND IN THE NEWS, President Gerald Ford and Israeli premier Yitzhak Rabin begin a two-day White House conference to discuss ways in which they can calm tense diplomatic relations in the Middle East.