You probably don't need to use a course since the GRE is a slightly modified version of the SAT (not to minimize the exam...). I'd say get your hands on some GRE books (Kaplan and Princeton are about the same, but some people prefer one over the other) and as many paper tests that you can stand to work on. Take about two months max to go through the materials and do problems (both on paper and computer based) and you should be just fine.