By Sue Zeidler

LOS ANGELES (Reuters) - Several musicians and pop stars -- whose work is at the heart of the Napster debate -- cheered a federal appeals court ruling on Monday that signals the end of the "all the music you can download for free" era.

In a ruling that Napster officials admitted could force the wildly-popular song swap service to close down, the 9th U.S. Circuit Court of Appeals on Monday said Napster must halt the sharing of songs by millions of users without the permission of their copyright owners.

"The court's decision ... confirms that Napster was wrong in taking not only Metallica's music but other artists who do not want to be a part of the Napster system and exploiting it without their approval," said hard rock band Metallica, which filed its own suit against Napster in addition to the music industry's landmark copyright infringement suit, which was the subject of Monday's ruling.

While the music industry got a strong boost in its efforts to shut down Napster on Monday, the record labels have yet to come up with anything remotely like it that offers so much music so easily to so many fans. While most recording artists like to be paid for their music, some performers find the broad access to a mass audience very appealing.

Rap singer Chuck D and the modern rock bands Smashing Pumpkins, Limp Bizkit, the Rosenbergs and Ben Folds Five, are supporters of Napster.

"I think the day of the lazy artist is over with," Chuck D said at an Internet conference a few months ago. "I think it's back to earning the respect of the fans one by one."

Billie Joe Armstrong of the band Green Day struck a similar populist chord in defending the song-swap service.

"I just want my music to be out, and that's always been the main priority," Armstrong said.

"It was never really about getting paid. It was just getting people to hear my music and say, 'Hey, I like your song.' So if Napster wants to put my song out so people can download it or whatever, let 'em do it," he said.

But many others shared those sentiments of Metallica and Dr. Dre -- another rap artist, who also filed a lawsuit of his own against Napster.

"When I worked 9 to 5, I expected to get a paycheck every week. It's the same with music," said controversial rapper Eminem. "If I'm putting my heart and all my time into my music, I expect to get rewarded for that. And if you can afford to have a computer, you can afford to pay $16 for my...CD."

Jimmy Buffett agreed, calling unlicensed trading of copyrighted music over the Internet "probably the most serious thing that can undermine an artist's catalog."

"All of a sudden, there's not value there, because everyone can get what you have for free," he said.

Some superstars like Sting say, however, that whether they like it or not, the technology is here to stay and the recording industry will have to reinvent itself in response to the Napster phenomenon.

"I do not think the genie will go back in the bottle," Sting told Reuters in an interview. "People are attracted to this idea of downloading music, but our society works on people being paid for their efforts, and it's just a matter of that catching up with the technology.

"Everything's going to change. The music industry will change and we'll have to be prepared to change with it," he said.

Still, with so much money at stake, most labels are not likely to accept a model that gives music away for free.

"I think the view would be that a settlement with Napster would be attractive, but all the labels have the same fundamental problem -- their contracts with artists," said Jeremy Silver, executive vice president of Uplister, an online music company.