In small glass bowl, combine raspberries, reserved syrup, water and cornstarch.
TO COOK BY INSTA-MATIC: Cover completely with plastic wrap; cook on COOK 8.
TO COOK BY TIME: Cook at HIGH 4 to 4 1/2 minutes, or until sauce is thickened; stir once.
TO COMPLETE: Stir well; chill.
Just before serving, add peaches.