Ok, here you go then:
 Code:
@ECHO off
FOR /f "tokens=3" %%a IN ('reg query^
 "HKLM\Software\Microsoft\Office\14.0\Outlook" /v Bitness') DO (
    SET answer=%%a
) 
IF %answer%==x86 (
    GOTO :x86
) ELSE (
    GOTO :x64
)

:x86
MSG * Office 2010 is x86
GOTO :END

:x64
MSG * Office 2010 is x64
GOTO :END

:END
pause

You can add support for more office versions, this is just my proof of concept :P
I KNOW the x64 bit is not fool proof but I can't be bothered, this is a PoC like I said.