I have a really old installer (legacy app) that we are trying to get running on a Windows 7 64 bit os.

Previously it has only been installed on Windows XP 32 bit. I get the following error when I try to run it:

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.

Contacting the software publisher is not an option (software is super old).

Is there a way to get this to work? Some sort of compatibility mode?

The only thing I have heard of that will work is a Virtual XP on the Win 7 box. The problem is that this software is a part of a whole software set. I would have to put all of the pieces on the Virtual XP or none at all.

Before I go down the road of putting it all on the virtual xp I would like to know that there is no way to get it all on the Win 7 os.