No less than 66% of companies plan to upgrade to Windows 7, albeit later rather than sooner, according to an October 2009 survey from Forrester Research, titled Windows 7 Commercial Adoption Outlook. But the latest Windows client from Microsoft is already the fastest selling operating system in history, having already sold in excess of 90 million copies in the first four months since launch. In this regard, Forrester Research has put together a new whitepaper designed to offer general guidance to adopters of Windows Vista’s successor. “Lessons Learned from Windows 7 Early Adopters” is available as a PDF via this link.