May 31

There are a ton of fixes on the net for Windows Update problems, this one, however, might be a one-stop-shop for Windows Update repairs

System Update Readiness Tool fixes Windows Update errors in Windows 8, Windows 7, Windows Vista, Windows Server 2008 R2, and Windows Server 2008

http://support.microsoft.com/kb/947821

Another and possibly quicker solution is the Windows Update Troubleshooter

http://support.microsoft.com/kb/956702

In case none of these solve the problem, nuke it by deleting the Windows Update files!
http://windows.microsoft.com/en-us/windows-vista/windows-update-error-80070002

If you run into issues deleting files in the instructions above, use Unlocker!

http://www.emptyloop.com/unlocker
When installing Unlocker, be sure to use the “advanced” installation option and remove the “install delta toolbar” option.