First off two of the rars of the pars were corrupt. I re-downloaded them and all was well.
Then I realized that I didn't put all the rars AND the numbered rars in the same folder while running quickpar. Once I did that, I was able to rebuild the ISO from them flawlessly and it burned great.
Sorry for not posting here to say I'd solved the problem! And thanks for the assistance.
Let's just say it takes real dedicated to get a fan edit this way... or else a great way to get rapidshare subscriptions (I'm just too cheap to download a fanedit when I own all the movies it's based on already).