In a large pot, bring salted water to a boil. Add the macaroni, and cook until tender, 8 to 10 minutes. Rinse under cold water and drain.
In a large bowl, combine the mayonnaise, vinegar, mustard, sugar, salt, pepper and celery salt. Stir in the cooked macaroni, bell pepper, onion and celery. Then gently stir in the hard boiled egg.
Cover the salad with plastic wrap and refrigerate for a minimum of 4 hours. Don't even think of tasting it until it has been chilled for 4 hours-- preferably longer.