Low Fat Banana Walnut Muffins

Heat oven to 350*.Lightly spray two 9x5x3 pans with non-stick veg spray. In small bowl, stir together sour cream and baking soda, set aside. In large bowl, beat sugar and margarine on medium speed of electric mixer until well blended. Add sour cream mixture, banana, and vanilla; beat until smooth. fold in chips and nuts. Pour batter evenly into prepared pans. Bake 45 to 55 minutes or until wooden pick inserted in center comes out clean. Cool 10 minutes. Remove from pans to wire rack;immediately wrap in plastic wrap. Cool completely before slicing.