In a large saute pan, heat the oil. Add the red pepper flakes and garlic and saute over medium heat just until the garlic begins to turn golden. Next, add the canned tomatoes, with their juice, and the sun-dried tomatoes and stir to combine. Then add the sugar, basil and salt and pepper and bring the mixture to a boil. Reduce the heat and simmer the sauce for 10 minutes. While the sauce is simmering, cook the penne in boiling salted water. Drain the pasta well and return it to the pot. Pour the sauce over the pasta and stir to combine well. Stir in the ricotta and parmesan cheeses and cook over medium heat until heated through. Serves 4.