In addition, the CEO of the San Francisco office of Grey Worldwide is leaving the Grey Global Group agency for McCann-Erickson WorldGroup, where he'll be head of global strategy.
Casey Jones, CEO and a co-managing partner of Grey San Francisco, will remain in the Bay Area and work primarily on the Microsoft account at McCann-Erickson, part of Interpublic Group of Cos.
Last month, Mr. McLaren, who was executive vice president and director of client services on Microsoft, successfully led McCann's efforts to consolidate Microsoft's customer relationship management account at McCann's MRM and WPP Group's Wunderman. He is relocating to New York.
Harry Corshan becomes worlwide director on the Microsoft ad account for McCann.
Microsoft spent $400.2 million in measured media for the first 11 months of 2003, and $306.1 for 2002, according to TNS Media Intelligence/CMR.
Meanwhile, in a statement, Grey said the San Francisco office will continue to be managed by the two other co-managing partners, Bill Burkart and Betsy Sperry.