In a small bowl mix graham cracker crumbs, margarine, and sugar mixture. Press onto bottom and sides (3/4 of the way up) of a 9-inch springform pan. Chill while preparing cake.

In a large mixing bowl beat cream cheese on medium speed until fluffy. Add sugar, flour and vanilla. Beat until combined. Add eggs, one at a time beating until just mixed. At low speed, beat in sour cream.

Pour into crust.

Bake at 325 for about an hour to an hour and fifteen minutes until center is almost set.

Cool on wire rack for 30 minutes. Loosen sides of pan. Continue cooling.

Refrigerate at least three hours. Serve plain or with topping.