1.In A Large Microwave-Safe Bowl, Combine The Potatoes, Carrots, Celery And Water. Cover And Microwave On High For 7 Minutes, Stirring Once. Add Green Pepper And Onion; Cover And Microwave On High For 4-5 Minutes Or Until Crisp-Tender, Stirring Once. Pour Into A 2-Qt. Microwave-Safe Baking Dish Coated With Nonstick Cooking Spray; Set Aside. 2.In A Microwave-Safe Bowl, Heat The Margarine, Covered, On High For 40-50 Seconds Or Until Melted. Stir In The Flour, Salt And Pepper Until Smooth. Gradually Add Milk. Cook, Uncovered, On High For 2-3 Minutes Or Until Thickened And Bubbly, Stirring After Each Minute. Stir In The Cheese Until Melted. Pour Over The Vegetables. Stir In Ham. Cover And Microwave On High For 4-5 Minutes Or Until Heated Through.