According to Bloomberg’s earlier report on Microsoft’s desire to encourage users to upgrade to more expensive versions of Windows 7, operating system software accounts for 28 percent of the company’s $60.4 billion in annual revenue and is its most profitable business.
Collins Stewart analyst Sandeep Aggarwal projected that Microsoft could rake in as much as $1.5 billion in additional revenue from the release of Windows 7. ZDNet reported that, of that $1.5 billion, nearly two-thirds of it will come from upgrades--which we assume means licenses from owners of Windows XP and Windows Vista.

Full story: tomshardware.com