BRUSSELS, Belgium -- A European Union court ruled yesterday that Microsoft Corp. must immediately share some trade secrets with competitors and produce a version of its Windows operating system stripped of a program that plays music and video.

The ruling thwarts the software giant's attempt to delay implementation of an EU antitrust decision designed to have a deeper impact than Microsoft's settlement with the U.S. government.

Microsoft said it would restrict its compliance to the European market, and analysts said the financial impact would be minimal.

The company's stock was barely nicked, trading down 10 cents to $26.97 a share in late afternoon trading on Nasdaq.

EU spokesman Jonathan Todd said the ruling "preserves the effectiveness of antitrust enforcement, in particular in fast-moving markets."

Implementation of the March decision will benefit computer users by expanding their choice of media players and workgroup servers and will stimulate innovation, Todd said.

Seattle-based RealNetworks Inc., maker of a rival to Microsoft's digital media player and Microsoft's last big commercial opponent in the case, praised the decision. The company's deputy general counsel, Dave Stewart, said his company can now compete "based on the merits of products and services rather than the power of Microsoft's monopoly."

The order only requires Microsoft to distribute the alternative version of Windows in Europe; Microsoft said it had no plans to distribute it elsewhere. Existing users of Windows won't be affected. The version stripped of Windows Media Player will cost the same as the regular product.

Brad Smith, Microsoft's top lawyer, said the company would supply the alternative version to computer makers in January and retail distributors in February.

Under the court order, any company in the world can license the software blueprints, Smith said. But companies can only use that information to develop and distribute software in Europe, not worldwide.