Apple will introduce its long-awaited iTunes for Windows service on October 16 at a special Apple event in San Francisco.

The event's invitation reads: "The year's biggest music story is about to get even bigger." The invite features Apple's familiar icon for its service and its iPod – a silhouetted figure on a coloured background holding an iPod, reports MacCentral

The company launched its iTunes Music Store for Mac on April 28, 2003. Since then, information disclosed by the company shows it to be selling approximately 500,000 tunes each week.

Apple's success in delivering a Mac-only service was prelude to the debut of an ever-increasing assortment of varying Windows-only services in the US. These include, MusicMatch and the forthcoming Napster 2.0 service.

While Needham & Co analyst Charles Wolf estimates the online music distribution market could be worth $3 billion on 15 per cent of the existing music market, the industry is shaping up to be extremely competitive.

Profit margins are also slight, with an estimated 35 cents on every dollar, from which companies must pay maintenance, administration and other charges. Wolf said that at a profit of under 10 cents per song, the market doesn't represent a major profit opportunity for Apple.

Captive market

Apple's true advantage in the current market is that its service works on Macs, unlike its competitors. This means it has a guaranteed base income and market from which to operate. In competitive terms, this offers Apple a market advantage.

Apple's other advantage is the popularity of its iPod MP3 player, which a recent Look-Look survey said was one of the top three items US kids wanted to take with them on their return to school.

The company has consistently said its strategy in the market is to help generate more iPod sales. Apple chief financial officer Fred Anderson has called it a "Trojan horse" to help boost sales of the product, which is also available for Windows.

Apple hopes to beef-up Mac sales by encouraging Windows-based iPod and iTunes users to switch.

Apple has doubled its US consumer market share over the last two years, partially through its Switch campaign.