Microsoft today has released Windows 7 Service Pack 1 which is now available for free download. Like most of the Service Packs for MS Windows, this service pack contains all the security and recommended updates that you would usually receive through Windows Update. The setup file has a size of 538MB and 903MB for 32-bit and 64-bit computers respectively.
HDMI audio performance is one of the major updates in Service Pack 1, which also includes RemoteFX to provide a rich 3D experience for remote computing.
If you choose to install Windows 7 SP1, open Windows Update and it will prompt you to download the service pack. You can also download SP1 directly from Microsoft Download Center.
In addition to Windows 7 SP1, Microsoft also released Windows Server 2008 R2 SP1 (also available for free).