OK it seems everyone has lost faith in me since this hasn't been implemented within 72 hours of the original post already so here is that stage its at:
The current version of vbulletin has a captcha option but PHP needs to have a gd library. I've been busy the past few days so haven't had time to set it all up which is why it hasn't been implemented yet.
Thank you for your response, all we were doing is asking, your post answers the question.