Forrester analyzed the operating systems of 400,000 client computers from 2,500 companies that surfed to its Web site in the last year to come up with its data.

The numbers point to problems that corporate IT staffs must solve, said Gray. "Even with Windows 7 as the dominant corporate OS, IT managers will continue to be challenged by increased device and OS diversity," he wrote.

Windows XP and Vista use in the enterprise have declined in the last 12 months, while Windows 7 and Mac OS X have gained ground. (Data: Forrester Research.)

Gregg Keizer covers Microsoft, security issues, Apple, Web browsers and general technology breaking news for Computerworld. Follow Gregg on Twitter at or subscribe to . His e-mail address is .

in Computerworld's Operating Systems Topic Center.