The News Corporation, making one of its largest bets on the Internet, announced today that it is paying $580 million in cash to acquire Intermix Media Inc., a Los Angeles-based company whose chief asset is MySpace.com, a Web site that is enjoying surging popularity with young audiences.

The acquisition's price is sure to ignite debate about valuations and durability of new media companies because MySpace, the main attraction among Intermix's 30-odd Web sites, is only two years old.

MySpace.com is a youth-oriented music and "social networking" site that has grown to more than 16 million monthly users. Its members spend hours on the site, exploring areas devoted to personal classifieds, music, blogs, video games and chat rooms.

Several prominent music groups, including the Black Eyed Peas, R.E.M. and Nine Inch Nails, have introduced their latest releases by streaming them on MySpace. Also, major advertisers including Procter & Gamble and Sony Pictures have advertised on the site, and NBC ran a streaming preview of the comedy "The Office" earlier this year. According to News Corporation, MySpace attracts the fifth-most page views of any Web site.