Not sure how it works, but you can't install an executable file in OS X. I would imagine that you have to install a virtualization setup that came with Virtual PC, then inside virtual PC you open setup.exe
It's sometimes hard to return opened software. Hopefully the place you bought it is understanding of your mistake and lets you return it. Be sure to explain why you're returning it and (if at all possible) exchange it for the Mac version.
It's sometimes hard to return opened software. Hopefully the place you bought it is understanding of your mistake and lets you return it. Be sure to explain why you're returning it and (if at all possible) exchange it for the Mac version.