Banana Pineapple Dessert

1 1/2 cups graham cracker crumbs
1/4 cup granulated sugar
1/3 cup margarine or butter, melted
3 bananas, sliced
8 ounces cream cheese, softened
3 1/2 cups cold milk
2 small boxes vanilla flavor instant pudding
20 ounces crushed pineapple, drained
8 ounces Cool Whip