Preheat oven to 350 F. Grease and flour a tube or bundt pan; set aside. Sift flour, baking powder and baking soda; set aside. In a separate bowl, cream together butter and 2 cups sugar. Add eggs to creamed mixture, one at a time, mixing well after each addition. Add vanilla to creamed mixture and blend well. Alternate adding flour mixture and sour cream to creamed mixture, mixing well after each addition. In a separate bowl, mix together cinnamon, 1/2 cup sugar and finely chopped pecans. Spoon a layer of batter into the prepared pan. Sprinkle a portion of the nut mixture onto the batter; cut into the batter with a knife. Repeat layers until all batter is used, ending with the nut mixture on top.Bake at 350 F for approximately 45 to 60 minutes or until toothpick inserted in center comes out clean. Cool in pan; turn out onto a cake plate and drizzle powdered sugar glaze on top. Powdered Sugar Glaze:In a small bowl, combine powdered sugar and vanilla. Stir in milk or orange juice. Stir in additional milk or orange juice, 1 teaspoon at a time until glaze is smooth and of drizzling consistency. Makes about 1/2 cup.