MS MinWin, aka do what UNIX has been doing for ages

Back in 2003, Microsoft assembled a team of engineers to rethink the lowest levels of Windows, so that the OS could be more easily slimmed down and secured to run in servers and embedded applications. That project, called “MinWin,” has now started to bear fruit.

Inside “MinWin”: the Windows 7 kernel slims down - Ars Technica