I haven't bought this game yet, but when I get my Xbox Fable 2 is top on my list. I was reading about it and someone said that you're either good or evil, AND pure or corrupt. And that you could be good and corrupt, or evil and pure. How is that possible? What's the difference between the two in the game?

The difference is mostly how people react to you as well as some of the the quests available to you