By Paul Thurrott

"For three years now, I've been charting the progress (or lack of progress) Microsoft has made with its next generation Windows operating system, code-named Longhorn. It all started back in January 2002, when I released my first iteration of The Road to Windows "Longhorn": What we know about the next version of Windows. The goal was to separate fact from myth. In that article, I exposed numerous Longhorn frauds and discussed some of the features Microsoft was then known to be including in Longhorn. Some of these, like WinFS (then identified only as a "SQL Server .NET-based file system) have since been canceled and will appear in a future Windows version. Others, like Windows Movie Maker 2 and a Windows Media Player refresh, have since shipped independently of Windows because of Longhorn's ever-increasing delays.

In May 2003, I followed up this original Longhorn preview with The Road to Windows "Longhorn" 2003, which featured concrete Longhorn information culled from that year's WinHEC trade show. It also included Microsoft's first public Longhorn release schedule (RTM in 2005, ahem), a detailed look at the product's componentization, and an overview of the Desktop Compositing Engine (DCE). However, in an August 2003 update, I revealed Longhorn's Aero user interface for the first time.

Then, in August 2004, I wrote the third installment, logically dubbed The Road to Windows "Longhorn" 2004, after Microsoft publicly revealed that it would delay WinFS and ship Windows XP/2003 versions of key Longhorn technologies, such as Avalon and Indigo. Microsoft also committed to a final release schedule for Longhorn, noting that the software would be delivered in 2006. Not late 2006, mind you, but mid-year. In November 2004, I updated that article with detailed Longhorn and Office 12 beta schedules which highlighted many of the milestones those releases would experience en route to their May 2006 final releases.

A new schedule
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.

A living document
Like all of my "Road to Longhorn" articles, I'll be updating this version throughout the year as new information arises. Two obvious updates will occur in April 2005 and September 2005, when the WinHEC and PDC 2005 shows occur, respectively. But as any other updates come up, I'll post them here."

--Paul Thurrott
January 11, 2005
Updated January 12, 2005; January 13, 2005

source: Paul Thurrott's SuperSite for Windows