Preheat oven to 350. In a large skillet, melt margarine and saute onions. Add rice and stir until grains are well coated. Add stock, wine, and all peppers. Boil gently until rice is cooked (about 40 min). Into the hot mixture fold in celery, cheeses, sour cream (or yogurt). Turn into a 9" x 13" baking dish treated with vegetable spray. Bake at 400 for 20 minutes or until golden brown.