This is important to remember if you are troubleshooting problems in your Office programs and you need to disable add-ins. If you are not modifying the correct registry data (because you do not realize you are running 32-bit Office on a 64-bit version of Windows), then your changes will not change the add-in behavior.
COM add-ins register themselves in the Windows Registry under either the HKEY_CURRENT_USER or HKEY_LOCAL_MACHINE hives. But, if you are using a 64-bit version of Windows, the subkey under HKEY_LOCAL_MACHINE will vary depending on the bitness of your Office installation. Please see the following table for the correct registry location for the different combinations of 32-bit/64-bit versions of Office and Windows.
COM add-in registry location under HKEY_LOCAL_MACHINE
Microsoft Outlook 2013, Microsoft Word 2013, Microsoft Excel 2013, Microsoft Outlook 2010, Microsoft Word 2010, Microsoft Excel 2010, Microsoft Office Outlook 2007, Microsoft Office Word 2007, Microsoft Office Excel 2007, Microsoft Office Outlook 2003, Microsoft Office Word 2003, Microsoft Office Excel 2003