About 2 hours before serving or early in day: Chop walnuts. In small bowl, combine walnuts, cinnamon, and 1/2 cup sugar; set aside. Preheat oven to 350°F. Grease and flour 10-inch tube pan with removable bottom. (If you like, wrap outside of pan bottom with foil to prevent any leaks.) In large bowl, with mixer at low speed, beat margarine and 2 cups sugar just until blended. Increase speed to high; beat until light and fluffy, about 5 minutes. Reduce speed to low; add milk and remaining ingredients; beat until well mixed, constantly scraping bowl. Increase speed to high; beat 2 minutes, occasionally scraping bowl. Spoon two-thirds of batter into pan; sprinkle with half of nut mixture; spread evenly with remaining batter. Sprinkle with remaining nut mixture. Bake coffee cake 1 hour and 5 minutes or until toothpick inserted in center comes out clean. Cool cake in pan on wire rack 10 minutes; remove from pan. Cool cake completely on wire rack. Makes 16 servings. Each serving: About 420 calories, 20 g fat, 87 mg cholesterol, 295 mg sodium.