CBS had the top-rated program but ABC was the most-watched network in prime time last week, ratings from the A.C. Nielsen Co. showed Tuesday. "Sarah, Plain and Tall," a movie based on a 1986 children's book by Patricia MacLachlan, was the week's big winner, attracting viewers in about 21.5 million homes. As for its Sunday night competition, NBC's movie "In Broad Daylight" was watched in about 12.8 million homes, while the first part of ABC's "Son of the Morning Star" was seen in about 10.9 million. Overall, however, ABC averaged the largest prime-time audiences, with CBS second and NBC third. ABC's best showing came with the three-hour "American Music Awards." The full list of ratings is on F13.