Beat butter, margarine and sugar (1 1/2 cups) until creamy.
Add the eggs, one at a time, and continue beating.
In a separate bowl, stir together flour, baking powder, and baking soda. Add to the creamed mixture alternately with sour cream, mixing after each addition.
Add vanilla, and mix until completely incorporated.
In a small bowl, mix chopped nuts, sugar (4 T.) and cinnamon.
Prepare a Bundt pan by greasing generously, and lightly dusting with flour.
Pour 1/3 of the batter into the bottom of the prepared Bundt pan. Smooth into a consistent layer with a knife. Sprinkle with 1/2 of the cinnamon sugar mixture.
Pour an additional 1/3 of the batter over the cinnamon sugar layer, smooth again with a knife. Sprinkle with the remaining 1/2 of the cinnamon sugar mixture.
Spread the remaining 1/3 batter on top the cinnamon sugar layer, and smooth with a knife.
Bake in a preheated 350 degree F oven for 1 hour.
Remove from the oven, and let cool for 1 hour in the pan.