The OS will be released to manufacturing in the first week of August, and new systems running the software will be generally available to the public on October 26. The news was announced by Windows group president Steven Sinofsky during Microsoft's annual sales meeting.
Enterprises won't have to wait until Halloween. Microsoft previously said they'll be able to start downloading final Windows 8 bits as early as August.
The new operating system will be available in just four editions: Windows 8, Windows 8 Pro, Windows 8 Enterprise, and Windows 8 RT. The last is Microsoft's official name for Windows On ARM, which will run on tablet chips manufactured by Qualcomm, Motorola, and Nvidia, as well as Redmond's own Surface tablet.
By comparison, Windows 7 was available in six editions, including Starter, Home Basic, Home Premium, Professional, Ultimate, and Enterprise.
[ Want the new version of Microsoft Office? You may need to upgrade your operating system, too. See Office 2013 Won't Run On Windows XP, Vista. ]
Users of Windows XP, Windows 7, or Windows Vista will be able to purchase and download Windows 8 Pro for just $39.99. The program, which starts with Windows 8's general availability in October and runs through January 31, 2013, also lets users install Windows Media Center for free once they've completed the upgrade.
The upgrade experience will differ depending on which version of Windows users are currently running.
Windows 7 to Windows 8 offers the most seamless upgrade, as users' settings, personal files, and apps will remain intact. From Windows Vista, settings and personal files are preserved, and from XP, only personal files will make the jump, although apps can be reinstalled after the upgrade is complete.
Windows 8 represents the biggest break with previous versions since the debut of Windows 95, which introduced the Start button, Task Bar, and other Windows staples. Windows 8 replaces the Start screen with Live Tiles, part of Microsoft's new Metro interface.
Microsoft is counting on Metro to give its products a consistent look and feel across smartphones, tablets, and PCs.