Preheat the oven to 350 degrees. Melt the 1 1/2 sticks of margarine in a 9 x 13 pan.
Meanwhile, combine the flour, (1 1/2 cups) sugar, baking powder and salt. Add the milk to the dry ingredients and stir until not lumpy. Pour the batter over the melted margarine. Drain the can of peaches (save the juice) and then place the peaches randomly over the batter. Then pour the peach juice over all. Then sprinkle the 1 cup sugar evenly on top. Bake , uncovered, at 350 degrees for one hour, or until bubbly and beginning to brown.