In small microwave safe bowl, melt margarine and topping on high 1 mintue; mix well. Pour cereal, popcorn and peanuts into large resealable plastic bag. Pour topping over cereal mixture inside plastic bag. Seal bag and shake until all pieces are evenly coated. Pour contents into large microwave safe bowl. Microwave on high 1-1/2 to 4 minutes, stirring every minute. Spread on waxed paper to cool. Store in airtight container.