Kingpaul - if it matters to your paper, Star Wars and Call of Cthulhu, while using the d20 system, are NOT d20 games - they and their rules mechanics cannot be used in other games by d20 publishers until they are released in a system reference document.
Don't know if this works for your accuracy or not, but I thought I'd mention it. Same thing goes for systems such as Wheel of Time.
You also do not have one very important post-apocalyptic d20 game: Darwin's World, by a company called RPGObjects.