Hi baconmapletini,
Based on the list of Schools that you've alluded to, you're probably fine to take the GRE (and all things being equal, you'll likely perform better on that Exam - so it's to your advantage to take that Test).
Given what you've described about your general math skills, I still strongly advise that you put in some general math study/practice BEFORE you start a GRE Course. Learning and practicing Tactics is an essential aspect of scoring at a high level, but all of that work is still based around the assumption that you can do the basic math properly and relatively quickly.
For free math practice and help, I recommend that you set up an account at Khan Academy (
www.khanacademy.org). The site is completely free and makes the learning a bit more fun and 'game-like' (as opposed to the dry academic approach taken by most books). While the site is vast, you should limit your studies to basic Arithmetic, Algebra and Geometry. After spending a little time re-building those skills, you can start your GRE studies. You can also download two free practice GRE Exams from
www.gre.org.
GMAT assassins aren't born, they're made,
Rich