Cut potatoes into cubes. Place in cold water and bring to a boil, cook for 5 minutes. Drain well. Warm sausage and ham in butter add onions, pepper, and celery. Saute 5 minutes. Add flour stirring constantly. Add milk gradually. Remove from heat. Pace potatoes into a large buttered baking dish. Add other ingredients. Stir well. Pour over sausage and milk mixture. Bake at 350 degrees F for 30 minutes or until potatoes are tender and cheese is golden brown on top.