Microsoft's head of engineering for the Windows 7 operating system says there are 25 'feature teams' of about 100 employees each working on the upcoming replacement to Windows Vista.

Windows 7 teams work on anything from external features, such as user interfaces, to under-the-hood areas such as networking, according to Steven Sinofsky, Microsoft senior vice president for Windows and Windows Live engineering, in a Monday posting at the new "Engineering Windows 7" blog.

"We create feature teams with n developers, n testers, and 1/2n program managers," Sinofsky wrote in a four-page blog that introduced his views on managing large-scale software development. "On average a feature team is about 40 developers across the Windows 7 project."

Based on that arrangement, each feature team would appear to have about 40 developers writing code, an equal number of beta testers -- which Sinofsky separately described as "software development engineers in test" -- and about 20 program managers.

In other words, that would be 2,000 developers creating or testing Windows 7 code, overseen by 500 managers.

Microsoft's public relations firms declined to confirm or clarify those figures.

Sinofsky, who headed development for Microsoft Office from the 2000 to the 2007 versions before taking over Windows development from retiring chief Jim Allchin, defended the size of the Windows development team against criticism that they are no longer agile and are a major reason why the Vista operating system and other Microsoft software have arrived late with bloated codebases, suffering from 'featuritis'.

"Some have said that the Windows team is just too big and that it has reached a size that causes engineering problems. At the same time, I might point out that just looking at the comments there is a pretty significant demand for a broad set of features and changes to Windows," Sinofsky wrote. "It takes a set of people to build Windows and it is a big project. The way that I look at this is that our job is to have the Windows team be the right size -- that sounds cliche but [what] I mean by that is that the team is neither too large nor too small, but is effectively managed so that the work of the team reflects the size of the team and you see the project as having the benefits we articulate."

Scheduled to arrive in 2010, Windows 7 will include touch-screen technology and other new features. It will be fairly similar under the hood to Windows Vista in order to minimize application and device compatibility problems.

Sinofsky suggested that critics who think Microsoft should simply remove features from Windows or start over from scratch are being naive.

"I'm reminded of a scene from [the movie] Amadeus where the Emperor suggests that the Marriage of Figaro contains 'too many notes' to which Mozart proclaims 'there are just as many notes, Majesty, as are required, neither more nor less.' Upon the Emperor suggesting that Mozart remove a few notes, Mozart simply asks 'which few did you have in mind?'" he wrote.