In medium bowl, combine oats, sugar and margarine; mix well.
Spread in greased 9-inch square pan.
Bake in preheated 350° oven 13 minutes or until light golden brown; cool.
In small, heavy saucepan over low heat, melt chips.
Spread over oat mixture; sprinkle with nuts.
Refrigerate until chocolate is set.
Cut into 2x11/2-inch bars.
Store in tightly covered container in refrigerator.