After years of preparation, McDonald's is ready to serve fresh, cooked-to-order beef in many of its burgers, backed by what promises to be a lot of marketing. It's the latest signal the world's largest restaurant chain is responding to what customers want. The Golden Arches is gearing up for the national debut of fresh (as opposed to frozen) quarter-pound beef patties, which comes one year after McDonald's announced its "hot off the grill" plans and four years since the world's largest restaurant began working on it. Fresh quarter-pound patties are now in about 3,500 U.S. restaurants and most of the rest of the Golden Arches' 14,000 U.S. locations should have them by early May.