my GMAT is scheduled on 19th.even i am hovering in the range 590-650 .but i am not losing hope bcoz i feel most of the practice tests are exagerrated.The main point to remember is that u have to get the first 10 questions right so spend more time and concentrate a lot on those questions since they have a great impact on your score.even on the exam dont worry if u havent got a few of the later questions right bcoz they may be pretesting questions which are not scored so carry on and do your best but do not worry at anytime.
apply the same strategy for POWERPREP test 1/2 days bfore your exam and see the difference.
PLs do not carry anxiety to the exam and believe me miracles do happen it could be possible that the first time u score 700+ is actually the real exam day otherwise there is always a second time ,its not the end of world .
pls let me know your score on email@example.com
bye and cheer up now