On the heels of Philips Electronics' deal to become the sole sponsor of "NBC Nightly News" next week, Microsoft has done the same with a broadcast of ESPN's "SportsCenter." Microsoft bought out the flagship 11 p.m. ET version of "SportsCenter" last night, airing seven minutes of commercials during the hour--down from the program's usual 15. The technology giant's initiative focused on its Xbox 360, which is facing a major challenge from the just-released Sony PlayStation 3, as the holiday season approaches. Microsoft is hoping to give its "SportsCenter" buyout legs by extending the sponsorship online over the next three weeks. The spots last night directed viewers to a Web site, where they are asked questions about the ads. If they get three of five correct, they are entered into a sweepstakes.