The battle for digital music format dominance between Apple and Windows Media Audio (WMA) may force Microsoft to offer overt help to digital music outlets.

Dozens of music stores exploit WMA, but Apple continues to take 70 per cent of the market with iTunes Music Store. "So Microsoft has been quietly shifting some of its marketing muscle to back a few of the rival stores – particularly Napster," reports the New York Post.

Despite its dominance of the desktop OS – with Apple's global market share falling below 2 per cent, according to Merril Lynch – Microsoft doesn't want Apple to become so dominant that it forms the standard for digital music distribution.

Microsoft uses its own doublespeak to suppport its software, talking up the "diversity" of WMA. Nielsen SoundScan reports that the dozen digital music services using this format have seized just 30 per cent marketshare.

Yankee Group analyst Michael Goodman told the Post: "The iPod is the 800-pound gorilla".