For a 32-bit adapter, the BizTalk Server Administration Console uses the HKEY_CLASSES_ROOT branch in the registry to obtain custom adapter configuration. If a 32-bit adapter is installed on a 64-bit server, the BizTalk Serve Administration Console instead uses the HKEY_CLASSES_ROOT\Wow6432Node\ branch for adapter configuration data.
http://msdn2.microsoft.com/en-us/library/aa561871.aspx