http://www.mathtv.com covers almost everything (except stats) covered on the quantitative section, from basic math to calculus, and its FREE once you register. The tutor is actually the author of the textbook i used in my trig class.
p.s; scroll down for the Calculus section.
The Kaplan book is not enough. Are you taking Calculus next semester? If you are, i suggest buying the required textbook early, or get one from the library, so you can practice a few problems