I think just making it so you can't post for a month, would be better. Then after (Please before you go on to say that this is stupid im not done here) a month that they could not post (Maybe we wouldn't tell them how long so they wouldn't just wait until posting time) and when their time is up, they would get an email from the admin or something. The email would require them to take a quiz, and send an email asking for posting privileges. The admin would be able to judge the intellect of the user by the score on the test and how well he can write in the email IE a person who would be like " Omhgz I lov Teh airsoft I sh9t like BBq guns all teh time in street its fun wann be tlkin tu u guyz about Guzn shi" would not be accepted.
Short version for those who didn't want to read
-No post for a month
-Month is done, they get email for small Quiz
-Quiz is passed, they email admin to let them post (It would be a good idea to mention that they must tell the admin in the email if they can't fluently write english because of nationality or whatnot)
-Admin judges their intelligence by the email and decides to let them on.
-User posts no questions that aren't awnsered in the faq and wont bother us with 1337 speak
It would require someone who would wan't to weed through the users.