I don't think the original message should be included when you reply. For that purpose you can use quote. Otherwise it is very hard to read the replys and they would get very big and long.
*hint* Btw, when you press reply and scroll down a bit you can see the message you are replying to. *hint*
But quote should definately have a reference to the original poster.
(How do you spell >definately< ? <img src="/ubbthreads/images/graemlins/winkwink.gif" alt="" />)