For anyone else running into this issue it stems from the fact that Boot Camp version 5 assumes you are installing a 64-bit Windows OS and so the setup.exe is 64-bit. Should you be attempting to install a 32-bit copy of Windows you will want to create the setup.exe with a copy of Boot Camp version 4.
Hope this helps anyone else running into the issue.
As a side note, manually installing the drivers does also work.
You can find links for the various versions of Boot Camp here:
Just find the correct model and version of windows and download the Boot Camp version provided by the link.
Note that there are a variety of versions of 4 available so it is important to make sure you find the correct model in order to get the correct version.