QDR Updates are Offices Updates from MS to fix a general problem (security issue, major issues). QFE (Quick Fix Engineering) Updates are made for a specific problem and are only available per request. These fixes are not tested against all combinations of installed Updates and can cause problems. You should only install such a fix, if you have the problem mentioned in the KB article. If you have applied such a fix, the version number is 20xxx to indicate that the file is from a QFE Fix. If you install a QDR Update that updater takes a look at you current installed file and checks if the file is version 16xxx (offical update or RTM version). If this is true the installer installs the 16xxx version of the update otherwise if the fileversion of your installed file is 20xxx (file from a QFE Update) the installer takes the 20xxx version. Because you have used the RTM version of Vista, the installer found the shell32.dll in version 16386, so the installer installed the shell32.dll in version 16513. But I have no idea, why the installer places the Shell32.dll Version 20628 inside the WinSxS folder.