How To Troubleshoot Windows 7 Service Pack 1 Installation Issues @ NGOHQ.com
Quote: "A new service pack always brings some excitement, but unfortunately it also brings new issues too. Just a few days ago, Windows 7 Service Pack 1 RTM build was leaked, and there have been already reports of installation problems. Even yours truly, has encountered one. In fact, that's why Microsoft hasn't released SP1 officially yet; they are waiting for developers and OEMs to ensure drivers and 3rd party software are 100% compatible with SP1.
First of all, I bet you wondering what's so cool about SP1? Well, SP1 brings 625 hotfixes, most of which weren't released to Windows Update. Additionally, SP1 also brings improved HDMI audio performance and support for an AVX (Advanced Vector Extensions) instruction set that was introduced in Intel Sandy Bridge processors. So I can't blame you for wanting to install SP1 as soon as possible, but if you're afraid of installation issues, or already suffering some – we're here to help."
Link:
www.ngohq.com/news/19268-how-to-troubles...allation-issues.html 
