Windows 7 Service Pack 1 is quite close to being released to manufacturing, reportedly. This piece of information comes from a third-party source, and was not confirmed by Microsoft in any way. In fact, while it’s not 100% certain, it appears that Windows 7 SP1 could have already hit the RTM development milestone.

The Redmond company has been extremely quiet on the progress of the Windows 7 SP1 development process, and the evolution from Release Candidate to RTM makes no exception to this rule.

And while there were voices claiming that Windows 7 SP1 would RTM ahead of the end of 2010, the software giant was immovable when it came to refusing to share a timetable with the public.

Wzor published what it claims are Build strings from various Windows 7 branches as they were on December 24, 2010, just ahead of Christmas, namely: win7 branch: 7601.17125.101210-1930; win7sp1_rtm branch: 7601.17514.101119-1850; and win7_spdev branch: 7601.17125.101221-1630.

Build 7601.17514.101119-1850 could be the final release of Windows 7 SP1, having been compiled on 19 November 2010, but there is no guarantee of this, with work still continuing on the first upgrade to the latest iteration of the Windows client and server platforms.

The Redmond company did confirm repeatedly that it’s aiming to release Windows 7 SP1 RTM to the public in the first quarter of 2011, although it failed to provide a specific availability deadline.

At this point in time early adopters can grab Windows 7 SP1 RC and test drive the release.

Considering the fact that SP1 is considered a minor upgrade for Windows 7, users of the client won’t be able to notice any differences between Windows 7 SP1 RC and the RTM release.

The same goes for customers running Windows Server 2008 R2, although for them the service pack does introduce new features such as RemoteFX and Dynamic Memory.

Windows 7 Service Pack 1 (SP1) Release Candidate (RC) Build 7601.17105.100929-1730 and Windows Server 2008 R2 Service Pack 1 (SP1) Release Candidate (RC) Build 7601.17105.100929-1730 are available for download here.