I've heard it argued that the essential difference between Sci-Fi and Fantasy is past vs. future. I've also seen it said that Fantasy is good vs. evil and is more religious, where Sci-Fi is our side vs. their side and is typically godless, or at least religion is discussed less. And then theres the magic vs. technology you said.

Not disagreeing, just saying that... I'm confused about it. Well, not really. I don't think it comes down to JUST ONE of those things being the difference between them. Its all of them. Next question, if there are all these differences, why are Science Fiction and Fantasy so often spoken in the same breath? :D

I'm just rambling, ignore me :D