X-Com was and still is genius, Apocalypse is awesome too.
Not really looking forwards to the new fps.
Try:
http://www.xcomufo.com/x1faq.html
That always helped me sort out my installation problems for all of the x-com series. As far as I'm aware Valve have a pre-configured version that you can get for around $5 which isn't much. Saves any faffing around with configs.