Hi born222,
Before switching your studies to focus on a different Test, you should do the necessary research into the Programs that you're interested in - in that way, you can be certain which Exam Scores are accepted and you can plan from there. If some of the Programs that you're interested in don't accept a GRE score as part of the application, then you'll end up limiting your application options (and then you might end up having to take both the GMAT and the GRE, which you would likely find excessive).
If you're interested in the GRE, then you can download 2 free practice Multi-Stage Tests (MSTs) from
www.gre.org.
GMAT assassins aren't born, they're made,
Rich