Melt margarine in a large nonstick skillet over medium-high heat. Add garlic and bacon; cook until bacon begins to brown. Reduce heat to medium; stir in flour. Gradually add milk, stirring with a whisk until blended; cook, stirring constantly, until thickened and bubbly. Stir in cream cheese and pepper; cook, stirring constantly, until blended. Add Parmesan cheese; cook, stirring often, until cheese melts.
Add hot fettuccine to ham mixture; toss well. Serve immediately.