The OPUC.DLL file is an activex control (Office Products Update Control) used by the Office Update site to scan the user's computer to determine if any Office applications require updates. The latest version of OPUC.DLL can be found at http://office.microsoft.com/officeupdate/content/opuc4.cab Unzipping the CAB file results in two files, OPUC.DLL version 12.0.5551.1000 and the associated OPUC.INF file. Merely copying the OPUC.DLL file to the %WINDIR% folder is insufficient, the OPUC.DLL file must be registered. If the installation program does not register the file it can be done post-installation using the command line %WINDIR%\SYSTEM32\REGSVR32 /s OPUC.DLL However, this is still not enough to get a successsful update scan, there is a second step of determining if the office installation is genuine, you will be prompted to download and install a second activex control, the office geniune advantage activex control. This can be downloaded at http://go.microsoft.com/fwlink?LinkId=58813 The file you download from this linke is OGAControl.CAB, unzipping the CAB yields two files, OGACheckControl.dll version 220.127.116.11 and OGAControl.inf Again, merely copying the DLL file to %WINDIR%\SYSTEM32 is insufficient, it must be registered using the command line %WINDIR%\SYSTEM32\REGSVR32 /s OGACheckControl.dll If both these steps are properly performed, the office update engine scans the user's installation without the necessity of downloading and installing any activex controls.