Sports-themed events powered CBS to yet another decisive ratings victory last week. Buoyed by Monday's NCAA championship and Sunday's Masters, the Eye net won the week among total viewers and adults 18-49. ABC, paced by Desperate Housewives (the week's top show) and the best-ever results for Grey's Anatomy, finished a distant No. 2. Over on cable, Discovery's cheesy Supervolcano drew 5.1 million viewers, the channel's best showing in nearly two years.