Just seven months after being named as Microsoft\u2019s security czar, Ben Fathi has set his sights on a new job.Starting in the next few weeks, Fathi will head up development of the core components of the Windows operating system, and the Security Technology Unit that he runs will be absorbed into the company\u2019s Trustworthy Computing team, led by Scott Charney.The changes are part of a reorganization of Microsoft\u2019s core operating system development efforts, announced Thursday. Microsoft has changed the top-level organization of its Microsoft\u2019s Core Operating Systems Division team, and created new groups within this division, each focused on a different aspect of the Windows platform.The plain-speaking Fathi had replaced Mike Nash, who had been the public face of Microsoft\u2019s efforts to lock down its operating system from attack for several years before him.Microsoft has improved its reputation for security of late, but over the past few months there has been a spike in the number of reported vulnerabilities in its software and the total number of patches issued by the company. On Tuesday, the company issued patches for 26 bugs in its software, the largest single-day patch release in recent memory.By merging the Security Technology and Trustworthy Computing units, Microsoft brings together two groups with very similar purposes.Fathi\u2019s unit had been chartered with leading "Microsoft\u2019s efforts to provide customers with a more secure platform," according to Microsoft\u2019s website. The Trustworthy Computing team, on the other hand, was created to "promote a safe, private and reliable computing experience for everyone."The new Trustworthy Computing team will be one of five units within the reorganized Core Operating Systems Division, which is headed up by Jon DeVaan, senior vice president of engineering strategy. DeVaan reports to Kevin Johnson, who along with Jim Allchin is co-president with the platform and services division.The Core Operating Systems Division was formed in December 2003 to improve the technical quality of Windows. In a statement, Microsoft called these recent changes "an extension of [the division\u2019s] original mission," and said they are "designed to provide more clarity and focus" to the group.The new groups within the division include a Windows Engineering System and Services team, a Windows Core System team and a PC Hardware team.The changes will take effect when Microsoft finally releases Vista to hardware manufacturers. This is expected to happen fairly soon, as the company has said it plans to have Vista in the hands of business users by year\u2019s end.By Robert McMillan, IDG News Service (San Francisco Bureau)Check out our CIO News Alerts and Tech Informer pages for more updated news coverage.