US District Judge James Ware last week rebuffed Microsoft's request to have an antitrust case against it held in a Washington state court.

Microsoft is the target of an antitrust suit by RealNetworks filed in a Californian court.

The Judge said in a filing that despite the fact that Microsoft, of Redmond, Washington, and RealNetworks, of Seattle, are both Washington corporations, it is appropriate for the case to remain in California.

"RealNetworks has satisfied this Court that important and considerable evidence on this issue is concentrated in the Northern District of California," Ware wrote in his ruling on Microsoft's request.

In a lawsuit filed in a federal court in California last December, RealNetworks asserted that Microsoft has illegally used its monopoly powers to control the digital-media market. RealNetworks is seeking damages that could exceed $1 billion.

In a motion heard on March 1, Microsoft had requested that the trial be moved to Washington state, where it would be "considerably less burdensome" to the employees of both companies as well as "less disruptive of their businesses." RealNetworks countered that numerous third-party witnesses it intends to call are based in California, justifying the location of the trial.

"RealNetworks has identified numerous companies in this district who allegedly have been directly impacted by Microsoft’s anticompetitive conduct. Therefore, California has a more substantial interest in adjudicating this case," the judge wrote.

Potential witnesses identified in the ruling include Acer, Apple, eMachines, Fujitsu America, Gateway, Hewlett-Packard, Toshiba America Information Systems, Sun Microsystems, Limelight Networks, Cnet Networks, Sony Online Entertainment, Yahoo, Warners, DreamWorks and Walt Disney.