Detect OS version 32/64bit in script

I am using Winbuilder with Win8.1SE and i have numerous programs that have 32bit and 64bit executables for the same application.
I prefer to use 64bit Windows but there is also a requirement for 32bit Windows on older x86 architecture.
Is there a command that I can use in Winbuilder to detect if Windows 32bit or 64bit is being used so that i can then add the relevant file version for the application?