Pasta Salad

1 box or bag or rigatoni noodles
1 lb bacon
½ red onion
3 stalks celery, chopped
1 pkg. Hidden Valley Buttermilk Ranch dressing mix
(prepare as directed on package)
1 8 oz bag shredded parmesan cheese

Cook the pasta according to directions. Rinse with cold water. Mix the dressing and pour over the noodles, bacon, celery and onion. Mix in cheese and refrigerate or serve immediately.