Melt margarine in a saucepan over medium heat. Add minced garlic, and saut 1 minute. Stir in flour. Gradually add skim milk, stirring with a wire whisk until mixture is blended. Cook, stirring constantly, 8 minutes or until mixture is thickened and bubbly.
Stir in cream cheese; cook 2 minutes. Add 1 cup Parmesan cheese, stirring constantly until Parmesan cheese melts.
Pour sauce over hot cooked fettuccine, and toss well to coat. Top fettuccine with remaining 1/4 cup Parmesan cheese, chopped parsley, and pepper.