[flower_child]

I think there's a difference between a "knowledge of good and evil" and a knowledge of obeying what your creator tells you to. There are certain things that even a baby knows by instinct. Adam and Eve knew without the knowledge of good and evil (or right and wrong, but I'm thinking there's a slight difference) that it was wrong to disobey God.

For the record, I think you took my analogy just a bit too literally.

As for the killing, you really have to read the Torah to understand what's going on. I struggled with it for a long time as well. When I actually buckled down and started reading the Bible, it was like a hundred lightbulbs went off in my head. But I'll still try to explain.

The idea was for the Jews to inherit the land that was promised to them through the covenant made with Abraham, Issac and Jacob. In reading the Torah, you'll see that following God's commands was a very very important thing to God. He had freed them from their oppression and promised to deliver them to a land "flowing with milk and honey." He wanted them to be pure and clean. He wanted them to be holy, and to be the best example to all mankind. The Jews are God's chosen people, and he wanted that to be completely obvious through their everyday lives. He wanted them to be sinless. So the point of destroying the occupants of the land they were going to was so that they would not fall back into sin. God did not want them to be corrupted by the people who were living in those lands. He did not want them to "worship gods that neither you nor your father's have known."
So basically, the idea was to remove any and all bad influences.

Another reason for this was that God wanted to show what the Jews were capable of with God strengthening them. God wanted the world to see that since the Jews followed Him wholeheartedly, they were indestructable.
God was setting an example. If you look at history, you'll see that in those times, such acts were considered great. It showed power and strength. It was the best way for the world of that age to understand God's power. It was how they would understand that there is no one that can compare to God; no power greater than or even equal to Him.

But like I said, to fully understand what's going on, you have to read the Torah. It also helps greatly to have a basic understanding of cultures of that age, and what they would relate to. You have to understand that what we look back on as atrocity, they looked at as majesty. You'll notice that many kings and leaders of that age were great conquerors as well. God was showing that he was "King of kings" in the best way that the world could relate to.

*edit* I want to put on the record that I don't feel good about saying "this is God's reason for doing this." What I've said here is the conclusion I've drawn from reading the Bible and from having a knowledge of history. I've spent a great deal of time praying about this, and this is what I feel is the right conclusion. It makes complete sense to me. Like I said, it's like lightbulbs going off in your head. I feel like this is God's explanation to me about his actions, because I have asked him what his purpose could possibly have been for having people killed like that. But I want the record to show that I am not a prophet and I do not have authority to say what God's purpose for his actions is.

*double edit* also, I'm going to bed, so I won't respond till tomorrow.