If you can install an additional dll on your computers, the following UDF will get the bit version of an exe. See notes in the thread.

PSGetBinaryType -
http://www.kixtart.org/forums/ubbthreads.php?ubb=showflat&Number=204276#Post204276

Thinking out loud...
Do a registry check for the path of your office installation
Since Word is included in all versions of office, use the path with WINWORD.EXE
Use the function above to check for 32 or 64 bit.