Sorry, I know this is from a long time ago - but I'm having this problem now and need to put a link-blocking mechanism in place for new members. It's my understanding that this would ban the posting of any links by a new member for the first X number of posts - whatever you set X to. But what if you'd like to also ban the posting of links for a certain number of days in addition to a number of posts?
I'd like to make spammers have to wait several days before being able to post links - in addition to forcing them to post a certain number of linkless posts. But I don't want to make it too tough because I don't want to annoy legitimate members. If I make the number of posts too high, real users will get frustrated and may leave. But if I make it too low it will be no problem for a spammer to get around. But if you could add a number of days to it, then it would deter most of the spammers and not annoy real users too much.