hey guys,
i agree that the destroyer is really good because it has so many questions and it covers pretty much everything. also, for bio, i used schaum's outlines for biology review. it covers everything and goes over plants/fungi/etc pretty thoroughly, but not overwhelmingly. i thought that it was better than the kaplan book, which i felt didn't delve deep enough. but like other people are saying...the actual test picks some pretty random nitpicky questions sometimes and it really is if you know it or not (or can guess the right answer or not).
as fas as GC, i went through my chem book and made a detailed review packet hitting all the main points. i also took the GC section on the practice oat on opted.org and used that to go over my strengths and weaknesses. i think that i used to get 280/290's on this section (i'm horrible at chem), but after doing all that i've gotten it up to 340/350.
anyways, hope that helps and good luck with studying!