1. Combine 1 1/2 cups all-purpose flour, wheat flour, and next 3 ingredients in a large mixing bowl. Combine milk, water, and margarine in a 4-cup liquid measuring cup. Microwave at HIGH 2 minutes; pour over flour mixture. Beat at medium speed with an electric mixer 2 minutes. Gradually stir in 2 cups all-purpose flour. Turn dough out onto a lightly floured surface; if dough is sticky, knead in remaining 1/4 cup flour. Cover dough with a large bowl; let stand 10 minutes.
2. Coat two 8 x 4-inch loaf pans with cooking spray; sprinkle evenly with cornmeal. Divide dough in half; shape each portion into a loaf, and place in pan. Cover and let dough rise in a warm place (85°), free from drafts, 1 hour or until dough is doubled in bulk.
3. Preheat oven to 400°.
4. Bake at 400° for 25 minutes. Remove loaves from pans, and cool on a wire rack.