Need discuss board script

[hoops]

I'm looking for a freeware php script for a discussion board with a lot of traffic. I don't need a forum and do not need people to register. I just need a threaded type of sime discussion board where people type their name and and email if they want then post a message. I need it so that people can reply to the message and need CAPTCHA. Please respond if you know of suck a script. I have searched on all of the major script sites and can't find exactly what I'm looking for.

Thanks!