Starting tomorrow, March 19, Windows 7 Service Pack 1 (SP1) will begin rolling out automatically to individuals via Windows Update. Not coincidentally, this change comes just weeks ahead of the end of mainstream support for the original, or RTM, version of Windows 7.

“Updating customers to Windows 7 SP1 is part of our ongoing effort to ensure continued support and improved security updates for customers who have not yet installed SP1,” a Microsoft representative noted. “Windows 7 SP1 was previously available on Windows Update but required user action to install.  Starting tomorrow, the installation will be fully automatic with no user action required for those who already have Automatic Update enabled.”

Windows 7 Service Pack 1 was released in February 2011, over two years ago.

Microsoft announced the change in a blog post noting that it only impacts PCs used by individuals. If you’re running Windows 7 in an environment managed by Systems Center Configuration Manager (SCCM), WSUS, or similar, you will still have full control over the release of SP1. Nothing has changed.

If you’re interested in the gory details, you can view the Windows 7 page on the Microsoft Support Lifecycle site. But what it boils down to is that mainstream support for the original, RTM (“release to manufacturing”) version of Windows 7 expires on April 9, 2013.

Mainstream support for Windows 7 with Service Pack 1 (SP1), to date the only service pack that Microsoft has released and plans to release for this system, ends “24 months after the next service pack releases or at the end of the product's support lifecycle, whichever comes first.” Assuming the latter, that would be January 13, 2015, though extended support will be provided through January 14, 2020, and will presumably be honored by our future robot overlords.