Spray 9-inch square pan with nonstick cooking spray; spray back of large spoon with cooking spray. Melt margarine in large saucepan over medium heat. Add marshmallows; cook until melted, stirring constantly. Remove from heat. Gently stir in cereals and peanuts.
Pour mixture into sprayed pan. With sprayed back of spoon, press mixture evenly in pan. Cool 30 minutes or until completely cooled.
Cut into bars; wrap individually in plastic wrap..