F R e N c H 3 z is correct that a lot of factors go into the selection of grad school students, but he is not correct that GRE is a joke. It is anything but a joke. Some schools take it very seriously, especially in years like this last one where some schools had 10 times the applications that they had in previous years. And it will depend upon the program you are trying for. Some schools/departments do have published GRE standards that must be met. Others it doesn't matter so much as long as everything else is strong. And it is a means of weeding out weaker students before they get to the door. PhD programs are particularly competitive since most are at least partially funded by the school itself. It is important to remember to keep in mind that GRE is a weak indicator of your potential ability to do well in grad school--grad school admissions committee care a lot about this!
It is also important to remember that the GRE is not really testing you verbal or mathematical aptitude. English and (grade 10) math are simply the means that they can use to test other things in such a way that students from any discipline can do the test without a prerequisite of specialized knowledge. With that said, the GRE is actually testing you on two rules of graduate school (1) knowing the system, and (2) jumping through the hoops. Successful graduate students always study for tests even when they are told not to study. Students who study for the GRE get an average of 300 points higher than those who did not. And even though ETS says you cannot study for it, those that study for it score much higher than those who do not. Furthermore, your ability to take the test seriously shows that you can apply yourself and study for a test even though it is complete poppycock. Finally, it is important to recognize that the math portion of the exam is not about math at all, it is a logic test using math. And yes, all sections of the test matter, even if your particular school says it does not. I know a guy who scored high 700s on the verbal and less than 300 on the quantitative. And even though he applied to schools that said they only looked at the verbal, 5 out of 6 rejected him on the basis of the low score. The truth is that no one wants a social scientist that cannot read a graph or an engineer who cannot construct a simple sentence. Both portions are important and both count even when the schools say they do not.
The good news is if you are going for a master's degree the GRE score will play less of a role for the admissions process. If you got at least 1100, you will be fine for the masters level. If you are applying for a top school for the PhD, you will need at least 1350. And if you are applying for a PhD at a lesser school you may be fine with a 1250. The silver lining in this is that people who take a master's before a PhD are more likely to actually complete their PhD as opposed to those who enter straight from their bachelor degree. It is also important to note that if you did really poorly and you retest raising your score by more than 200 points, be prepared to take the test a third time as their anti-cheating protocols kick in. They will consider you guilty until proven innocent and will not post your improved score until you can prove you didn't cheat by taking it a third time. And of course, you are paying for this third retest--there are no freebies with ETS. It isn't fair but it is their game and their rules.
If you would like to discuss this off-line, feel free to PM me. I'm right now at grad school and will be going through the application process yet again in the not too distant future.