Pour cereals into large bowl; set aside. In 1 quart microwave-safe bowl combine chocolate chips, peanut butter and margarine. Microwave on HIGH 1 to 11/2 minutes or until smooth, stirring after 1 minute*. Stir in vanilla. Pour chocolate mixture over cereals, stirring until all pieces are evenly coated. Pour cereal mixture into a large resealable plastic bag with powdered sugar. Seal securely and shake until all pieces are well coated. Spread on waxed paper to cool. Stovetop: Pour cereals into large bowl; set aside. In small saucepan over low heat melt chocolate chips, peanut butter and margarine until smooth, stirring often. Remove from heat; stir in vanilla. Continue as indicated above. Do not use reduced-fat margarine or butter as it may cause chocolate mixture to clump and will not coat the cereal mixture evenly. *Cooking time based on using 625 to 700 watt ovens. Nutritional Information Per 1/2 Cup Serving: Calories 230 ; Fat 9 g; Cholesterol 0 mg; Sodium 240 mg; Carbohydrate 33 g; Protein 5 g.