In particular, "Do you think Voldemort would have won the first war, had it not been for Harry 'defeating him'?" made me think. I sort of wanted to say 'yes' because the whole scenario involves the destruction of a core group of the Order.
Because if harry dies, that means James, Lily, Peter (supposedly), and Sirius are all out of commission in one huge blow. But then i caught myself thinking 'and they're the most important!' and had to tell myself 'whoah back'.
Because there are lots of other Order members. Order members who have years more experience and could easily be more powerful than a handful of idiots a few years out of Hogwarts. And there are loads more idiots just like them where that came from.
And the list of people who died as Order members that Moody reels off to Harry is impressive, even in its (probably) incomplete form. Clearly nobody thought the war was over when the Prewett brothers were killed, amazing as Moody says they were. Nobody said 'Caradoc Dearborn's had it, that's the end for us!'.
Now, on the other hand, if the random chain of events ending with Harry is the only way Voldemort can be defeated, i suppose this is all moot. But that seems a bit shady to me given the scope and possibility inherent in a magical world as varied as this one.
Maybe there is something special about Potters (Gryffindor blood, probably), maybe Voldemort had been killing them off on purpose for some time and that's why Harry has no relatives, and maybe both James and Harry being dead would have an import that only Dumbledore if anybody would realize.
But then again, there is a tendancy to read the Potters and the Marauders in general as more important than they might have really been just because we know the most about them, and virtually nothing about anybody else in the first war.
I mean, look at it this way: you have a group of people (50ish?) waging an underground war. three of them die, one joins the enemy. Is it the end of the war?
Clearly we're supposed to think that James and Sirius were hot stuff, but assigning import to that when not in light of Harry's Voldie Smiting Powers is tricky business.