Cook and measure out orzo into large bowl, set aside. Drain fruit. Cut cherries
In 2 qt. sauce pan, mix pineapple, oranges, sugar, and cornstarch. Cook on low to med. heat until mixture is thickened and bubbling, making sure to stir often. Add mixture to orzo. Add cut cherries and mix well.
Let chill 30 minutes. Fold in Cool Whip. Keep chilled till ready to serve.