Windows 7 Service Pack 1 is available for MSDN and TechNet subscribers
Microsoft has announced that the first service pack for Windows 7 and Server 2008 R2 is available to download for MSDN and TechNet subscribers. This is offered in three versions, one for 32- and two for 64-bit Windows (x64 and Itanium). All three will update both Windows 7 and Server 2008 R2, because both operating systems are based on the same kernel. The sizes of the packages are 550 MB (x86), 925 MB (x64) and 525 MB (Itanium).
This SP1 is mostly a collection of hotfixes and patches which are described in detail in the provided documentation. Few new features are included; Microsoft merely mentions RemoteFX (hardware-accelerated 3D graphics output in remote desktop sessions, only in conjunction with Server 2008 R2) and Dynamic Memory (dynamic assignment of memory areas of guest systems running Windows Server 2008 R2 Hyper-V). Shortly before the completion of SP1 development, it was revealed that Windows 7 would for the first time support the Intel Advanced Vector Extensions (AVX).
From 22 February Microsoft plans to offer SP1 for free download and also deliver it by means of the Windows Update feature. Being this close in time to the deployment through MSDN / Technet is unusual – in the past there was usually several months between the two dates. This does not necessarily mean that Microsoft is rushing this time to provide the service pack as a Windows Update; rather, it's that quite some time has passed since it was prepared for MSDN and Technet. According to the build number (7601.win7sp1_rtm.101119-1850), SP1 was in fact already finished by 19 November last year. Why Microsoft has sat on the release until today is unclear. Maybe this is due to pre-arranged schedules which could not be easily changed.
The installation of SP1 takes longer than an hour. It can only install on a machine on which Windows 7 has been previously installed, together with the more than 30 MB System Update Readiness Tool. This carries the patch number KB977821, so it clearly has nothing to do with the update KB976902, which Microsoft has been distributing for some time in preparation for the service pack using Windows Update.