In a large bowl mix first four ingredients and set aside. In a saucepan combine syrup and sugar. Bring to a boil, stirring often. Remove from heat. Stir in peanut butter and vanilla until well blended. Pour over Cheerios mixture you set aside in the beginning. Stir to coat all pieces. Spread mixture and press lightly onto a greased 15 X 10 X 1 inch pan or bowl. Let mixture cool. Cut into small squares. Recipe can be cut in half.