We use a Scada software application (32-bit) that has run on Windows versions since W95, and now up to W7, but in recent times with 64-bit machines we have never found a means to run it on 64-bit machines. Using a licence key we produce a runtime version for customers, but then they need to have 32-bit machines also.
The screen message displayed is;
"The version of this file is not compatible with the version of Windows you're running. Check your computer's system information to see whether you need an x86 (32-bit) or x64 (64-bit) version of the program, and then contact the software publisher."
You may find not all 32-bit software will run on 64-bit and if it is specialty software it may pay to trial it first.