AutoRun Wizard FAQ
Q: Can I autorun a different file for 32-bit Windows and 64-bit Windows? (41,965 views)
Yes, in the latest version of AutoRun Wizard you can specify if the file you want to autorun will execute on 32-bit or 64-bit operating systems. This is done by checking the checkboxes on the File Properties window.
If the target operating system does not match the os architecture, the file will not run. You could setup two different autorun files, one being a 32bit-setup.exe and a 64bit-setup.exe. On each of the File Properties you would check the box for only running on that particular operating system.