Deploy software with both 32/64-bit MSI installations

That should work fine. I have used the following logic in batch files to determine if the OS was 32 or 64 bit... (obviously replace the echo line with your command or GOTO statement)

@ECHO OFF
IF EXIST "%ProgramFiles(x86)%" (
echo "64-bit"
) ELSE (
echo "32-bit"
)

This has worked for me without problems.

In version 1.6 we are planning on offering a native conditional to determine, at  run time, the OS architecture. This way you can effectively say  what your current batch file says. If Arch is 64 bit run x.exe else run y.exe. 

So probably build into the MSI command the same thing PDQ does with the switches:

@ECHO OFF
IF EXIST "%ProgramFiles(x86)%" (

msiexec.exe /i "\\server\share\Application64.msi" /qb

) ELSE (

msiexec.exe /i "\\server\share\Application86.msi" /qb

)

Thanks for the update and advice in the meanwhile.

-Ken

Kind of. The native feature that we will use won't reference %ProgramFiles(x86)% to determine OS Arch. We will use a Windows API to determine whether the OS is 64 bit or 32 bit. Referencing the %ProgramFiles(x86)% variable is just a decent work around until this new feature is available.

I understand, was just referring to the script I'll use in the meanwhile.  Thanks for the clarification and this can be marked as "resolved".