Surely if you first check the bitness of the OS (if it's 32 bit you now know you have a 32 bit Office install) and if it's 64 bit then look in %ProgramFiles% (64 bit) or %ProgramFiles(x86)% (32 bit) for the Office folder (Office, Office10, Office11, Office12, Office14 or Office15) or else find the path of some common Office executable file such as Winword.exe or Excel.exe, you have your answer? Or am I missing something here? if this is some corporate thing, surely you know what your machines have installed anyhow?