LOS ANGELES - The superhero epic "X-Men: The Last Stand" proved magnetic over the Memorial Day weekend, taking in $120.1 million, the biggest opening ever for the holiday weekend. Preliminary estimates also gave the latest installment of the comic book franchise the fourth best three-day opening ever and the best single Friday in movie history with a gross of $45.5 million. The film's box office was the second-biggest one-day gross ever after last year's "Star Wars: Episode III." The movie exceeded expectations, including those of 20th Century Fox, which released it. "Wow," said Bruce Snyder, head of distribution at 20th...