Brussels, Belgium ? Microsoft Corp. is making several key changes to its forthcoming Windows Vista operating system in an attempt to soothe European antitrust worries, while keeping its worldwide distribution plans on schedule.

Brad Smith, Microsoft’s general counsel, said Friday the company agreed to change how people can set their preferred search service if they upgrade to Microsoft’s new Internet Explorer browser. The Redmond, Wash., company also has tweaked Vista’s security system to address concerns that the system was favoring Microsoft’s products over competing security offerings.

In addition, the company plans to have an international standards organization review a controversial new file format that will be included in Windows and the company’s Office business suite.

He said that was a step toward making the format available for other companies to license.

Even with the changes, which will be included in all versions the company ships worldwide, Microsoft said it still plans to deliver the long-delayed Vista to large businesses in November and consumers and small businesses in January.

The announcement follows many testy exchanges between Microsoft and European regulators, who remain embroiled in a long-running antitrust dispute about the current version of Windows.