Tony, is there are way to register where the posts are made? That way people won't just post 5 times quickly by saying "First" and such? I mean, you could just ban hammer them, but that would be sadness all around. That said, I like the idea, no "Why don't you buy sports equipment" posts in this forum will be great!
Unfortunately, there's no way to control where the five posts should be made, nor their length. That's a limitation of the software.
The good thing is that anyone who is really interested in being involved in the community won't have a problem making five posts. This precaution is primarily to deter professional spammers.
By the way, it's rather amazing how many spammers have been trying to get on to this site. Each day anywhere from 5 to 10 spambots attempt to register. Sometimes far more. And this is for a forum that hasn't even been publicly launched yet!!!
Thankfully these bots are pretty easy to outsmart.