Windows 7 PC buyers who made their purchase on June 2 or later--up until January 31, 2013--can visit a website that Microsoft has launched, enter their details, and await notification of Windows 8's availability, at which time they'll have the option to purchase the upgrade using a promo code.
"You should ... have your 25-digit Windows 7 product key that came with the PC handy as you may be required to enter this as part of the registration," Microsoft's Brandon LeBlanc noted, in a blog post.
The regular upgrade price for Windows XP, Vista, and Windows 7 systems purchased prior to June 2 is $39.
Users who purchase the upgrade will be directed to Windows.com, where they can install Windows 8 Pro through a download. Microsoft offers a number of tools, including Windows 8 Upgrade Assistant, to help make sure the process goes smoothly.
Windows 7 PC users must complete the upgrade by Feb. 28, 2013, to receive the discount.
[ Check out Microsoft's new productivity software. See Microsoft Office 2013: 10 Best Features. ]
Earlier this week, Microsoft released a version of Windows 8 that developers and other IT pros can use free of charge for 90 days in order to test the new OS.
The Windows 8 Enterprise Edition 90-day evaluation program makes the OS available as an ISO image in 32-bit or 64-bit editions. In addition to English, it's available in Chinese, German, Japanese, Korean, and several other languages.
Developers can access the software through the Windows Dev Center developer downloads page. "This is intended for developers building Windows 8 apps and IT professionals interested in trying Windows 8 Enterprise on behalf of their organization," Microsoft stated.
Trial versions of Windows 8 Enterprise are also available through MSDN subscriptions, the Microsoft Partner Network, TechNet professional subscriptions, and Microsoft's Volume Licensing and Software Assurance programs. The product must be activated online within 10 days of installing.
The evaluation edition expires in 90 days and cannot be upgraded to the full version. It has to be uninstalled before systems can be upgraded.
Consumers who want to try Windows 8 prior to October 26 can download the Release Preview from Microsoft's website.
Windows 8 RP is a mostly finished version of the operating system, though the more fully baked Windows 8 RTM offers some notable additions.