Thanks I'll go through this page :) point is I'm working full time and have a very little time to spend on preparation, but I'm going to do part of the tests while at work.. I also found one very good advice here:
http://www.www.urch.com/forums/just-finished-my-gmat/48749-740-gmat-510-740-47q-44v-my-full-debrief.html
what he wrote really inspired me.. :)