Preheat oven to 325 F. Grease a 12-cup bundt pan with margarine and dust with flour. In a medium bowl, mix 1 Tbs of flour and the brown sugar. Add peaches and mix until covered with sugar. Spread peaches around bottom of bundt pan. In a large mixing bowl, cream margarine and sugar. Stir in 2-1/2 cups flour, salt, baking soda and baking powder. Add vanilla, yogurt, egg and egg white then beat for 3 minutes at medium speed.
Pour batter over peaches and bake for about 1 hour or until a cake tester comes out clean. Cool for about 10 minutes before removing from pan.