FYI... Win7 SP1 goes "missing"...
'You do not have the option of downloading Windows 7 SP1 when you use Windows Update to check for updates'
- http://support.microsoft.com/kb/2498452
Last Review: April 24, 2012 - Revision: 11.0
"... To resolve this issue, follow the steps in the methods below..."
(See the site)