follow package directions to cook fettuccini. drain.
In a large sauce pan stir together cream cheese, Parmesan cheese, margarine and milk. Cook over low heat stirring constantly until smooth.
Add fettucini and toss lightly.
You can make this in the microwave. Add all sauce ingredients in a 2 quart microwave safe bowl. Cook 1 minute on high and stir with a whisk. Cook one more minute and stir. Then cook 30 seconds at a time until mixture is smooth and bubbly.
We often add cooked cubed chicken and/or broccoli to this. You can use the canned chicken or 2 cups of deboned rotisserie chicken. I often cook my broccoli and fettuccini together.