Paper or plastic, boxers or briefs, David Lee Roth or Sammy Hagar — the two men who fronted Van Halen couldn’t have been any more different. Roth was a flamboyant, loony ringmaster. Hagar was the cool older brother who would buy you beer. Both men will be inducted into the Rock and Roll Hall of Fame March 12 with Van Halen (Roth is even hitting the road again with his old band this summer), while an exhibit highlighting the 2007 class of inductees, which also includes Grandmaster Flash and the Furious Five, R.E.M., The Ronettes and Patti Smith, opens at the museum this month.