Windows 7 SP1 is now available for download available from Microsoft’s download Website, or via Windows Update,
Microsoft says Windows 7 Service Pack 1 is an update that does the following:
Helps keep PCs supported.
Provides ongoing improvement to the operating system, by including previous updates delivered over Windows Update as well as continuing incremental updates to the Windows 7 platform based on customer and partner feedback.
Makes it easy for organizations to deploy a single set of updates.
You need to uninstall any pre-releases of SP1 before installing
Download: http://windows.microsoft.com/en-US/windows/downloads/service-packs
