the best predictor of your GRE performance is your SAT performance. (more evidence that these tests mostly measure your ability to take similar tests.) so if your GRE scores are way lower than your SAT scores, you can be sure that with better preparation you'll do much better. in any case, if you've got two years before applying, definitely study and retake the test. preparation really can boost your scores. and good scores can make a huge difference in grad school applications and funding. (I'm a PhD who had decent undergrad grades but stellar GRE scores, and got a great fully-funded grad school slot in a humanities program based on the GRE scores.)