Combine sugar, margarine, and milk in heavy 2.5 qt. Saucepan; bring to full rolling bowl, stirring constantly. Continue boiling 5 minutes over medium heat or until candy thermometer reaches 234 °C F, stirring constantly to prevent scorching. Remove from heat; stir in chips until melted. Add marshmallow creme, nuts and vanilla; beat until well blended. Pour into greased 9"x13" pan. Cool at room temperature, cut into squares. Makes approx 3lb.