Place chicken in a large pot and add 2 quarts of water. Boil until tender (30 to 40 minutes). Reserve broth for cooking spaghetti. Cool, skin and remove bones. Cut into 1-inch cubes. In a skillet on top of stove, sauté pepper, onion and celery in oleo, until tender. Add soup tomatoes and chicken to sauté mixture, simmer. Break spaghetti in thirds. Cook spaghetti in chicken broth (about 2 quarts of broth, do not drain, leave in pot). Grate cheese. Mix chicken, soup mixture and cheese into spaghetti with broth. Mix together and pour into a 9" x 13" casserole dish. Bake at 350° for one hour.