In order to download and install Windows 7 and Windows Server 2008 R2 SP1 you must currently have a Release to Manufacturing (RTM) version of Windows 7 or Windows Server 2008 This article, KBĢ505743, provides some suggestions to improve your experience when you install Windows 7 SP1 from the Microsoft Download Center Web site, there are steps that you can take to make sure that you have a good experience when you install the service pack.
If you choose to install Windows 7 SP1 from the Note: Steps to take before installing Windows 7 Service Pack 1 from the Microsoft Download Center Windows 7 and Windows Server 2008 R2 Service Pack 1 (KB976932)