Bring a large pot of salted water to a boil. Add the pasta and cook until it is tender but still firm to the bite, about 8 to 10 minutes or follow package directions. Meanwhile, if you are using fresh garlic, peel and mince it. Drain the clams. If you are using parsley, rinse, pat it dry, and mince it. About 3 minutes before the pasta is done, heat oil in a skillet over medium-high heat. Add the garlic and cook until you get a whiff of its aroma, about 30 seconds. Stir in the clams and cook until they are heated through, about 1 minute. Add the white wine and simmer until some has evaporated, about 1 minute. Stir in the red pepper flakes or cayenne, add 1/2 cup of the pasta cooking water (this will create a more fluid sauce), and remove the skillet from heat. Drain the pasta in a colander and then return to the pot, off the heat. Add the clam sauce, and the parsley, if you are using it mix thoroughly. Serve immediately.