Cook and drain spinach noodles while doing the following: Drain mushrooms, but RESERVE LIQUID; set aside. Melt diet margarine in small saucepan. Add onion and celery; saute over low heat 3 minutes. Add mushrooms and flour and stir until flour is well blended. Add crabmeat and sherry; cook over low heat 5 mins. Combine sour cream substitute and reserved mushroom liquid, stirring well. Add sour cream sub. mixture, s & p to crab mixture, stirring well. Add 2 T. diet margarine to the cooked, drained spinach noodles and arrange noodles on a serving platter. Spoon crabmeat mixture over noodles.