Apple's iTunes Music Store is that offer free music-swapping. According to an NPD Group survey of US Internet users, iTunes was tied with Limewire for the No. 2 spot in March behind WinMX. iTunes and Limewire were each used by 1.7 million households, while, WinMX was used by 2.1 million households. AFP reports that millions are still downloading unauthorized songs and both Napster and RealNetworks also placed in the top 10 alongside P2P services like iMesh and Kazaa. NPD also said that four percent of Internet-enabled US households used a paid music download store in March 2005.

"One of the music industry's questions has been, when will paid download stores compete head-to-head with free P2P download services," said Russ Crupnick, president of the NPD Group's music and movies division.

The survey found that older consumers are more likely to be deterred by anti-piracy litigation efforts, and that younger users, including college students, are relatively undettered and continue to use free services, according to the report.

"That question has now been answered. iTunes is more popular than nearly any P2P service, and two other paid digital music offerings have also gained a level of critical mass. These digital download stores appear to have created a compelling and economically viable alternative to illegal file sharing."

The top 10 music sites were WinMX, iTunes and LimeWire, Kazaa, BearShare, Ares Galaxy, Napster, Morpheus, Real Player Store and iMesh.