Apple's iTunes Music Store is proving more popular than many peer-to-peer (P2P) file-sharing services, according to a report by research company The NPD Group. The MusicWatch Digital Service survey found iTunes in a dead heat with P2P service LimeWire, and ahead of others like Kazaa and iMesh.

The NPD Group estimates that four percent of internet-enabled households in the US used a paid music download store in March 2005.

A large number of those users were more than 30 years old and had an average household income of $83,000 (£45,000). NPD said that post-college consumers are more likely to buy music than steal it, compared to youngsters.

"They have diminishing free time, and more disposable income," said Russ Crupnick, president of the NPD Group's Music and Movies division. Crupnick called the results of iTunes and two other pay-to-play services on the top ten list — Napster and the Real Player Store — proof positive that "digital download stores appear to have created a compelling and economically viable alternative to illegal file sharing."

At the top of the list was WinMX, a Windows P2P service that NPD claims is used by 2.1m households. iTunes and LimeWire saw use by 1.7m households. Kazaa came in fourth, followed by BearShare, Ares Galaxy, Napster, Morpheus, Real Player Store and iMesh.

The survey was conducted by collecting data from Windows-based PCs used by 40,000 online panelists. The information compares March 2005 to March 2004 household activity of consumers who had acquired digital music either through paid services or P2P file sharing services.