In 1 quart microwave safe bowl, combine chocolate chips, Reesie's peanut butter, and margarine. Microwave on high for 1 1/2 minutes or until smooth, stirring after one minute. Stir in vanilla.
Pour chocolate mixture over cereals, stirring until all pieces are evenly coated. Poor cereal mixture into large zipper bag with powdered sugar. Seal securely and shake until all pieces are well coated. Spread on waxed paper to cool.