Microsoft announced Tuesday that Kevin Johnson, its former sales chief, would succeed chief Windows architect Jim Allchin next year when he retires.

Johnson has spent most of his 13 years at Microsoft rising through the company's sales and marketing ranks. He landed the top sales post two years ago and has since helped Microsoft keep up its double-digit growth, an impressive feat for such a large company.

Johnson is also one of six top executives who help chart Microsoft's strategy and direction alongside Chairman Bill Gates and Chief Executive Steve Ballmer as a member of the company's Senior Leadership Team. So when Microsoft handed over Johnson's sales responsibilites last month to its new chief operating officer, a former Wal-Mart Stores executive, Ballmer promised he had big things in store for Johnson.

Despite his talents, analysts said, Johnson may feel stretched in his new role as co-president of Microsoft's Platform Products and Services division.

"Jim Allchin is a very technical person; he's a Bill person," said Rob Helm, an analyst at Directions on Microsoft. "Kevin is fundamentally a Steve person. He's an excellent business man, but it's a very different skill set than what Allchin had."