The release schedule I published in The Road to Windows "Longhorn" 2004 was accurate at the time it was published. However, as is so often the case, Microsoft has revised that schedule. What hasn't changed is the May 2006 release date: While internal discussions at Microsoft recently questioned whether August 2006 would be more viable, the word has come down from on high: May 2006 is non-negotiable. Longhorn will be released to manufacturing in May 2006, according to senior Microsoft executives.

Here's the new schedule.

Longhorn Milestone 9 (M9) and platform complete
March 2005

Longhorn Beta 1
Late May 2005

Longhorn Beta 2
October 2005

Longhorn Release Candidate 0 (RC0)
Late February 2006

Longhorn Release Candidate 1 (RC1)
April 2006

Longhorn release to manufacturing (RTM)
May 24, 2006

Notice the inclusion of a RC0 build, which is unusual. The last time Microsoft shipped an RC0 build of a Windows product, I believe, was with Windows Millennium Edition (Me). RC0 releases are typically designed to give Microsoft's hardware and software partners enough time to develop drivers and compatible software in time for the final release of a product.

Microsoft briefly considered having only one beta release, but the company is now "firm" on two betas.
New product editions

Though these plans could change, Microsoft is currently planning to ship an amazing array of product editions, or SKUs, in the Windows Longhorn family. These are the currently-scheduled versions that will ship in May 2006:

Longhorn Starter Edition
Analogous to Windows XP Starter Edition.

Longhorn Home Edition
Analogous to Windows XP Home Edition.

Longhorn Premium/Media Center Edition
A premium superset of Home Edition that includes the Media Center functionality. Similar to XP Media Center Edition.

Longhorn Professional Edition
Analogous to Windows XP Professional Edition.

Longhorn Small Business Edition
A new product edition aimed at the small business market. Currently very similar to Professional Edition.

Longhorn Mobility/Tablet PC Edition
Analogous to Windows XP Tablet PC Edition.

Longhorn "Uber" Edition
A new product edition that bridges the consumer and business versions and includes all of the features from the Home, Premium, Pro, Small Business, and Tablet PC Editions (but not Starter Edition).

None of these product names are final, of course, and all versions except Starter Edition will ship in both 32-bit (x86) and 64-bit (x64) variants. One of the problems with this approach is that Microsoft will have a hard time communicating the differences between each SKU, in my opinion. It will be interesting to see how this develops. My advice would be to cut back on the SKUs and offer only consumer and business versions. The consumer version should include everything from Home and Premium/Media Center Editions, while the business version should include the features from Pro, Small Business, and Tablet PC Editions.

Also, though Microsoft briefly considered not shipping retail versions of Longhorn at all, and would have required users to acquire the OS with a new PC purchase, those plans were cancelled. As with Windows XP, the various Longhorn editions will ship in retail and OEM (PC maker) versions.

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