The two main editions will be Windows 7 Home Premium for consumers and Windows 7 Professional for business users.

"The first change in Windows 7 was to make sure that editions of Windows 7 are a superset of one another. That is to say, as customers upgrade from one version to the next, they keep all features and functionality from the previous edition," Mike Ybarra, Microsoft general manager for Windows, .

That decision represents a return to the version structure that Microsoft used for Windows XP.

As for the decision to focus on attention on just two versions, Ybarra said: "We think those two SKUs will meet most customers' needs," Ybarra said.

Home Premium will give consumers "a full-function PC experience and a visually rich environment in everything from the way they experience entertainment to the way they connect their devices," he said. Windows 7 Professional "is the recommended choice for small businesses and for people who work at home but have to operate in an IT-managed or business environment where security and productivity are critical. For those running , it will be a very logical move to Windows 7 Professional."