Hi siddddd,
While the GMAT has gone through some changes since you last took it (most notably the inclusion of the IR section and the removal of the Issue Essay), the general content and 'design' of the Test hasn't changed too much since you last took it. Since you scored 770 last time, and it's not likely that you've lost all of those skills, you would probably score fairly well if you took the GMAT today. As a starting point for this new round of studies, it would be a good idea to take a FULL-LENGTH practice CAT Test; you can download 2 for free from
www.mba.com (and they come with some additional practice materials). That score will give us a good sense of your current strengths and weaknesses and will help provide a basis for comparison as you continue to study. You should post back here with those scores and we can talk through your study plans.
GMAT assassins aren't born, they're made,
Rich