By default, the Windows Update client records all transaction information to the following log file:

%windir%\Windowsupdate.log

If you receive an error message on the Microsoft Windows Update Web site or from the Automatic Updates service, you can use the information that is included in the Windowsupdate.log log file to troubleshoot the issue.

Visit http://support.microsoft.com/kb/902093 for more information on how to read the log file

Hi,
Thanks for this guideline and very informative steps for read windowsupdate log file.