Vista successor will be monitored to ensure Microsoft toes the line.
A team of technical advisors to US antitrust officials has taken charge of a copy of Microsoft's Windows 7 operating system.
The news was revealed in a status report filed with US District Judge Colleen Kollar-Kotelly at the end of February.
Little is known about the upcoming successor to Windows Vista, but the technical committee will examine the software to ensure that Microsoft continues to abide by antitrust rulings set in 2002.
"The technical committee has begun to review Windows 7. Microsoft recently supplied the committee with a build of Windows 7, and is discussing testing going forward," said the report.
"The technical committee will conduct middleware-related tests on future builds of Windows 7."
The committee dates back to the 2002 decree, which also required Microsoft to help rival parties integrate any new feature added to Windows that meets the definition of a "Microsoft middleware product".