The changing of the guard inside the Microsoft division building the company's flagship product continued Tuesday, with several top executives working on the Windows Vista operating system given new assignments after the product is complete.

Brian Valentine, who at one time may have been in line to succeed outgoing Windows head Jim Allchin, is moving to an undisclosed role at Microsoft after Vista — now two years behind schedule — is complete. Valentine, who joined the company in 1987, is senior vice president of the Windows Core Operating System Division.

"The old guard of Windows who oversaw Vista, for better or worse, has been moving out," said Rob Helm, director of research at Directions on Microsoft, a Kirkland-based company that provides independent industry analysis.

Microsoft, which is expected to put Vista in broad distribution early next year, is making the changes to ensure "a strong plan and leadership team for the future and ... accommodate strong employees who will desire a change after completing such a significant project," the company said in a statement.

Jon DeVaan will move to the Windows operation and will co-lead the core operating system division — which is responsible for developing the operating system and integration across platforms — until Valentine departs.

DeVaan, previously senior vice president of engineering excellence at Microsoft, has been working closely with Chairman Bill Gates to address challenges of developing large software systems.

"If anybody needs help knowing how to build big software, it's the Windows group," Helm said.

DeVaan has worked closely with Steven Sinofsky and was formerly his boss in the division overseeing Microsoft Office.

Sinofsky was named in March to head the Windows and Windows Live efforts at the company, one of eight units within the Microsoft Platforms and Services Division. That division, one of Microsoft's three major operating units, is led by Kevin Johnson, division co-president with Allchin.

"What this reflects is Steve Sinofsky taking control of the group that produces Windows," Helm said, adding that the executive has brought other top technical people from Office to Windows.

Valentine is a Gen. George Patton-like figure within Microsoft, an inspiring leader who "drives the troops forward" — something he's likely been doing a lot of in the push to release Vista, Helm said.

"He's tired, I'm guessing, because he's famous for pushing the team," Helm said. "I don't know what new role he'll be seeking, but he's done an awful lot for the company."

Microsoft also announced Tuesday that upon completion of Vista, Dave Cutler, a senior technical fellow, and Amitabh Srivastava, corporate vice president in the core operating-system division, will work directly for Chief Software Architect Ray Ozzie on the Internet-services effort dubbed Live.

Also, Gary Flake and the Live Labs team he heads will report directly to Ozzie.

Benjamin J. Romano: bromano@seattletimes.com