As promised, Microsoft today released the final version of Windows 8 to MSDN and TechNet subscribers.
But it also posted a 90-day evaluation copy of Windows 8 RTM (release to manufacturing) that anyone can download.
At approximately 1 p.m. ET, members of TechNet began reporting that Windows 8 RTM was available.
"Downloading Windows 8 Enterprise now, with an Enterprise Multiple Activation key," said Ken Schannen, in a message posted on the TechNet discussion thread. "I also see Windows 8 Pro with 3 keys available."
Others chimed in that they had start downloading, too.
Not surprisingly, some subscribers said Microsoft's servers were sluggish under the strain. "TechNet is dying under the stress of all the downloads," said someone identified only as "Mercutio84" on a different thread.
The MSDN (Microsoft Developer Network) download site listed all versions of Windows 8 RTM (release to manufacturing), including Windows 8, and Windows Enterprise. The last targets businesses that have volume licensing plans in place.
Two weeks ago, Microsoft announced that Windows 8 had reached the RTM milestone, and would be available to MSDN and TechNet subscribers today, Aug. 15. Companies with Software Assurance licensing agreements and members of the Microsoft Partner Network will be able to grab Windows 8 starting tomorrow,
Year-long TechNet subscriptions start at $199, while the least-expensive MSDN subscription -- which lets members access only operating systems -- costs $699.
But Microsoft has also made available the Enterprise edition of Windows 8 RTM to anyone willing to invest some download time.
Although the company said the 90-day trial copy was "intended for developers building Windows 8 apps and IT professionals interested in trying Windows 8 Enterprise on behalf of their organization," those who don't fit into those two categories -- enthusiasts eager to get their hands on the finalized code, say -- aren't blocked from downloading the eval edition.
Computerworld was able to register for the trial and begin the download process of Windows 8 Enterprise RTM without incident. The download generates an .iso file, or disk image, that must be burned to physical media, such as a DVD or a flash drive, or installed in a virtual machine.
Unlike the versions distributed via TechNet and MSDN to paying subscribers, the evaluation expires after 90 days of use. At that time, Windows 8 blackens the desktop background, displays a persistent notice that the OS is not genuine, and most draconian of all, shuts down the PC every hour without giving the user a chance to save works in progress.
When the evaluation period expires, users will have to replace it with a purchased copy or another operating system, and reinstall all applications, other software and files. "It is not possible to upgrade the evaluation to a licensed working version of Windows 8," Microsoft warned.
If a user downloads and launches the evaluation copy today, it will run until Nov. 12, 2012, about two-and-a-half weeks after Microsoft officially launches Windows 8.
The trial copy of Windows 8 Enterprise must be activated within 10 days of its first launch, but Microsoft said a product key was not required. It is available in Chinese, English, French, German, Italian, Japanese, Korean, Portuguese and Spanish.
To download the 90-day try-before-you-buy -- available in 32- and 64-bit versions -- start at this Microsoft website.
The 32-bit trial tips the bit scales at 2.4GB.
Anyone can try out the RTM of Windows 8 for 90 days.
Gregg Keizer covers Microsoft, security issues, Apple, Web browsers and general technology breaking news for Computerworld. Follow Gregg on Twitter at @gkeizer, on Google+ or subscribe to Gregg's RSS feed. His email address is email@example.com.
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