Microsoft has announced that it had wrapped up work on Windows 7 Service Pack 1 (SP1), and would start delivering the major upgrade on 22 February through Windows Update.

The company said it had reached the "release to manufacturing", or RTM milestone for both Windows 7 SP1 and Windows Server 2008 R2 SP1, and was shipping the code to PC and server makers today.

Customers who subscribe to either TechNet or the Microsoft Software Developer Network (MSDN) can download Windows 7 SP1 starting Wednesday, 16 February, the same day companies with volume licence agreements can get the upgrade. The general public must wait until the following Tuesday, when SP1 hits the Windows Update service.

Microsoft typically reserves the last Tuesday of each month for shipping non-security updates.

Microsoft has said several times that Windows 7 SP1 would not include any new features specific to the operating system, but would instead be composed of the security patches and nonsecurity fixes that had already been issued via Windows Update. The only additions to SP1 include an updated Remote Desktop client designed to work with RemoteFX, a new technology that debuts with Windows Server 2008 R2 SP1.

RemoteFX is designed to improve the graphics performance of Windows 7 virtual machines hosted on Server 2008 R2 SP1 systems. Windows 7 SP1 also supports "Dynamic Memory," a feature in Server 2008 R2 SP1 that lets IT staff adjust guest virtual machines' memory on the fly.

Microsoft is pushing the benefits of Windows 7 SP1 to corporations, claiming that RemoteFX and Dynamic Memory would let computer makers design and sell low-cost clients that run Windows 7 in a virtual machine.

"These technologies will drive down the endpoint cost and reduce endpoint power consumption," said Michael Kleef, a senior technical product manager with the Windows Server group.