1. Cook linguine according to package directions, omitting salt and fat.
2. Drain.
3. Set aside, and keep warm.
4. Saute onion and garlic in margarine in a small frypan over medium heat until onion is crisp tender, set aside.
5. Combine sour cream, milk, and pepper in a small bowl, stir well.
6. Combine linguine, onion mixture, and sour cream mixture, toss well.
7. Sprinkle with parmesan cheese and parsley.
8. Serve immediately.