The European Commission appointed a British computer scientist Wednesday to oversee whether Microsoft Corp. is complying with a 2004 antitrust ruling that it had abused its near-monopoly in desktop computer systems to shut out rival software makers.

The EU executive named Neil Barrett as a trustee to monitor the U.S. software company’s compliance on the same day EU Competition Commissioner Neelie Kroes met with Microsoft Chief Executive Steve Ballmer to discuss general antitrust issues.