Windows 7 SP1 Installation Problems and Resolutions
If you are experiencing problems installing the SP1 update to Windows 7, the below solutions may prove helpful.
Pre-requisites
A good article on things to consider before you install SP1 is http://blogs.technet.com/b/joscon/archive/2011/03/08/general-guidance-before-installing-service-pack-1-for-windows-7-and-windows-2008-r2.aspx.
General troubleshooting
KB article 2498452, "You do not have the option of downloading Windows 7 SP1 when you use Windows Update to check for updates",
http://support.microsoft.com/default.aspx?scid=kb;en-US;2498452.
KB article 2529073, "Binary files in some USB drivers are not updated after you install Windows 7 SP1 or Windows Server 2008 R2 SP1",
http://support.microsoft.com/default.aspx?scid=kb;en-US;2529073.
Blog post on WSUS update revision issue, http://blogs.technet.com/b/wsus/archive/2011/05/27/windows-7-windows-server-2008-r2-service-pack-1-revision-issue.aspx.
Blog post "How to reclaim space after applying Windows 7/2008 R2 Service Pack 1", http://blogs.technet.com/b/joscon/archive/2011/02/15/how-to-reclaim-space-after-applying-service-pack-1.aspx.
Resolving specific errors
Error 0xC0000034
KB article 2533552, "An update that prevents a "0xC0000034" error message when you try to install Windows 7 SP1 or Windows Server 2008 R2 SP1",
http://support.microsoft.com/default.aspx?scid=kb;en-US;2533552.
KB article 975484, "Your computer may freeze or restart to a black screen that has a "0xc0000034" error message after you install Service Pack 1 on Windows 7 or Windows 2008 R2", http://support.microsoft.com/default.aspx?scid=kb;EN-US;975484.
X34 Error (Event ID 10)
KB article 2545227, "Event ID 10 is logged in the Application log after you install Service Pack 1 for Windows 7 or Windows Server 2008 R2",
http://support.microsoft.com/default.aspx?scid=kb;en-US;2545227.
Error 0xC0000009A
KB article 2534366, "0xC0000009A error message when you try to install Windows 7 SP1 or Windows Server 2008 R2 SP1",
http://support.microsoft.com/default.aspx?scid=kb;en-US;2534366.
Error 0x800f0a12
Blog post "Windows 7/2008 R2 Service Pack 1 fails with 0x800f0a12", http://blogs.technet.com/b/joscon/archive/2011/02/17/windows-7-2008-r2-service-pack-1-fails-with-0x800f0a12.aspx.
How to reclaim space after applying Windows 7/2008 R2 Service Pack 1
Error 0x8004a029
Blog post "Windows 7 Service Pack 1 fails with error code 0x8004a029", http://blogs.technet.com/b/joscon/archive/2011/02/21/windows-7-service-pack-1-fails-with-error-code-0x8004a029.aspx.
Error 0x800f0a13 Error 0x800f0826
Blog post "Windows 7 Service Pack 1 fails to install with 0x800f0a13 or 0x800f0826", http://blogs.technet.com/b/joscon/archive/2011/02/24/windows-7-service-pack-1-fails-to-install-with-0x800f0a13-or-0x800f0826.aspx.