Melt margarine in a large saucepan over medium heat; stir in flour, salt and pepper. Gradually stir in milk. Cook and stir until thickened and bubbly. Remove from heat. Add 1-1/2 cups Cheddar cheese; stir until melted. Stir in noodles.
Spoon half of noodle mixture into a greased 13x9-inch baking dish; top with Swiss cheese, remaining macaroni mixture then remaining Cheddar cheese.