One of the architects of Windows Vista is leaving Microsoft weeks after it emerged he would be re-assigned once the delayed operating system is launched.

Brian Valentine, the vice president for Microsoft's core operating system division, is reportedly leaving Microsoft after 19 years to join internet retailer Amazon.

His exit comes after it emerged Valentine was being replaced by the man currently in charge of Microsoft's engineering standards, Jon DeVaan, while no role had been earmarked for Valentine. It was the latest bout of change designed to finally get Windows Vista out the door and lay the groundwork for smoother delivery for future versions of Windows.

Former group vice president Jim Allchin is also headed out following a major restructuring last September. Allchin was responsible for Windows product delivery, engineering and technical architecture but was elevated to a broader, shared responsibility as platform and services division co-president with fellow co-president Kevin Johnson - formerly group vice president of sales, marketing and services. Allchin will leave Microsoft, after 16 years, once Windows Vista has shipped.

Windows Vista has been beset by delays, core architectural elements have been removed and the code base was reworked after as it became obvious the original vision could not be met.

Valentine led Windows code engineering for seven years and is joining Amazon as a senior vice president. Microsoft was unavailable for comment at the time of going to press®