NBC finally found a must-see-TV show for Friday night. It was the opening ceremonies of the 2004 Olympics in Athens, which scored big ratings for an Olympics held outside the U.S. According to the network, some 56 million people watched at least part of the show, tying the number who tuned into the opening ceremonies in 2000 in Sydney. An average of 25.1 million viewers watched the pageant and parade. In Nielsen terms, the launch was the third highest-rated among non-U.S. Olympic openers since the Rome games in 1960, drawing 14.4 percent of U.S. households. (Sydney was No. 2.) ''With the average American television household having 25 more channels to choose from than it did four years ago, it feels great to be right on the viewership levels of Sydney's opening ceremony," said NBC Sports chief Dick Ebersol in a statement.'' Aptly enough, the biggest audience for the show was in Salt Lake City, apparently still afflicted with Olympic fever after hosting the Winter Games two years ago.