Using a heavy large sauce pan, put in sugar and milk. Bring slowly to a rolling boil. (Rolling means when the liquid is boiling very fast, not small bubbles.) Let it boil for no longer than eight minutes, Stirring Constantly to keep milk from scorching. Remove from heat and add 8 ounces of marshmallows, 18 ounces of chocolate chips and margarine. Stir until melted and blended in well. Ad nut meats and vanilla. Spread on a large, ungreased pan and when cool cut into squares. This makes a large batch of fudge-great for gifts. Enjoy!