The PSPICE version is not available anymore, but the latest one released by OrCAD is called **OrCAD PSpice Designer **. This version is compatible with Windows 8.1 starting release 16.6. Yes, you can run PSPICE on Windows 7, but only the latest version. If you have an older PSPICE version, install the updates and then it should run properly.
For additional information contact the developers: http://www.orcad.com/about/contact-us