Preheat oven to 350 degrees F (175 degrees C). Grease and flour one 9x13 inch baking pan.
Cream together the butter and sugar until light and fluffy. Beat in the eggs one at a time. Add the cake mix, baking powder, salt, and vanilla extract; mix well. Stir in the nuts and fruits. Pour batter into prepared pan.
Bake at 350 degrees F (175 degrees C) for 30 minutes. Cool cake before serving.