By Aidan Malley

Published: 07:40 PM EST

Although often considered the de facto choice for music sales, Apple's iTunes media player has just recently surpassed RealPlayer and is now second only to Microsoft's Windows Media Player for streaming media.

Website Optimization cites new research from Nielsen Online that shows the Apple software crossing the threshold in April 2007 and maintaining a near-total advantage over RealPlayer up to the most recent survey in December, which showed almost 35.7 million unique iTunes users versus Real's 27.6 million.

Microsoft's Windows Media Player, which comes bundled with most editions of the stronger-selling Windows operating system, remained the dominant software with nearly 75.9 million users.

But iTunes alone showed any consistent growth, according to the Nielsen results. The jukebox program's overall user base grew by 26.8 percent between December 2006 and December 2007 while all others slowed or reversed course. RealPlayer's use dropped by 17.5 percent, while Windows Media Player was "essentially flat" throughout all of 2007 and slipped by 58,000 users, or less than one percent.

Even Apple's own QuickTime software, which forms the backbone of iTunes' music and video playback, saw its usage for streaming media drop by 8.6 percent over the same timeframe.

A report in early 2007 accurately predicted that Apple's move to second place would occur by mid-2007 but followed an earlier study from a year before which prematurely suggested the changeover would take place in mid-2006. In practice, iTunes traffic grew only modestly until a spike during the holidays -- likely triggered by iPod sales -- put the software within reach of RealPlayer's user share.