The sin of Adam: Ordained, or chosen (or both)?

So you thought I was finished postin', after a recent drought of activity here. Au contraire, my friend!

This post is in response to a discussion I had last night with my man, Mark Kupets. We got to talking about theology, and specifically, whether God chooses who will be saved, or if man freely chooses. This is my understanding of the process: because of the sin of Adam, man has a corrupt, sinful nature that does not allow him to seek God on his own. God moves in the hearts of the elect, and changes their desires by regenerating them, causing the regenerate to choose to place their complete trust in Jesus Christ for salvation.

But what about Adam? He didn't start off with an inherited sin nature. So did he freely choose to sin, or was it ordained by God? If the former is the case, then doesn't that place God in a reactionary position, where man acts and then God responds and plans around man's decision? If the contrary is true, then what role does the sin nature play, since in this scenario he was going to sin even though he didn't have the sin nature? And what does it say about God and His relationship with man? What are the implications of either scenario, and which scenario is most accurate, according to the Bible?

I also had a discussion about providence with Justin Stone last Tuesday. I think he discerned accurately by stating something like, "The root issue for me in this discussion is understanding the nature of God." Right on, Solid Stone.

And you, diligent reader? What say you about God and His relation to man?