1) Mix cracker crumbs with the powdered sugar. Melt peanut butter and 1 1/2 sticks of the margarine together and combine with crumb mixture, making sure to work together welt.
2) Spread in a 9 x 13 inch well greased pan packing down hard. Melt 1/2 stick margarine and chocolate chips until smooth. Spread over top of peanut butter mixture. When cooled and set, cut into squares.