PREHEAT oven to 350°F. Reserve 14 of the crackers; finely crush remaining crackers. Melt 1/4 cup (4 Tbsp.) of the margarine in medium bowl or saucepan. Add cracker crumbs and walnuts; mix well. Press 1 cup of the cracker crumb mixture firmly onto bottom of 9-inch pie plate; set remaining crumb mixture aside for later use. Stand reserved 14 crackers around edge of pie plate.
MELT remaining 2 Tbsp. margarine in large bowl or saucepan. Add eggs, corn syrup, sugar and vanilla; beat with wire whisk until well blended. Stir in remaining crumb mixture; pour into crust.
BAKE 20 min. or until center is set. Cool completely. Top with dollops of whipped topping just before serving. Store leftover pie in refrigerator.