The Recording Industry Association of America (RIAA) has won the first round of a legal fight to shut down Napster's file-sharing technology that allows an estimated 20 million users to access and swap MP3 files on their computers.

The senior executive vice president of the RIAA, Cary Sherman said: "We are pleased with the court's decision, this decision will pave the way for the future of on-line music. This once again establishes that the rules of the road are the same on-line as they are off-line and sends a strong message to others that they cannot build a business based on others' copyrighted works without permission."

Napster has to remove all copyrighted material from its service by midnight Friday (28 July). Napster's Hank Barry declared he will fight on, he is filing an appeal today.

Napster still faces more court time in San Francisco for the actual trial with the RIAA. Napster also faces individual lawsuits filed by Metallica and Dr Dre.