My GRE scores were extremely disappointing. However, I know that I do not do well on multiple choice tests, so instead of retaking them, I improved my application my getting some papers submitted for publication and focused on winning funding (SSHRC). After I did that I got into almost every school I applied to, even the schools that said they had high cutoffs for the GREs. Obviously, if you can improve your scores great...if not, it's not the end of the world, there are other ways you can improve your application.