"Empowered workers attracted to BYO [bring your own] device programs are quickly coming to expect Mac and iOS support," Gray wrote.
Forrester's operating system usage data in the enterprise shows the same trends as other analysis, including that by Web metrics company Net Applications, which tracks global operating use.
Net Applications pegged Windows XP's usage share in March 2011 at 54.4% and Windows 7's at 24.2%, the former slightly lower than Forrester's, the latter slightly higher. (By May 2011, XP's share had fallen to 52.4%, while Windows 7's had climbed to 25.9%.)
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 @gkeizer or subscribe to Gregg's RSS feed . His e-mail address is firstname.lastname@example.org .
Read more about operating systems in Computerworld's Operating Systems Topic Center.