Not a medical student (in another professional school now), but I did take the MCAT and scored well on it. All I really used to study was that big-ass book from Kaplan, which is supposed to be a pretty comprehensive review of material on the test, and you can supplement with your own notes/materials from undergrad as you feel is necessary. I just went through that book one small section at a time - do one section of physics, one biology, one chemistry, etc., all the way through the book.
I also took lots of practice tests. I think that's especially important, you need to become comfortable with the test, get your pacing right, etc.
I pretty much ignored preparing for the essay and ended up doing mediocre on it, but I don't think that matters so much.
But honestly, the fact that you're doubting your desire to go to med school just because you have to take the MCAT would indicate that you need to think hard about what you really want to do. A career in medicine, starting with taking the MCAT, is not something that should be approached half-assed.