Cook the macaroni according to directions on the box. Remove from heat, drain, and add soup, 1/4 cup of the margarine, sour cream, shredded cheese, and the cheese packet from the box. Do not use milk as directed on the box.
Pour in a small casserole dish and top with crumbled crackers. Melt the remaining margarine and pour over the crackers. Bake in a preheated oven for 25 minutes.