Youll get a better idea if you look at my site, gonna try invision to see if it will fit

If that is the case that it can only be 500 pixels wide does anyone know of another Forum that could be made to fit on my site ?

It needs to be 400 pixels  to fit on my site really, http://www.themaradonas.co.uk/home.php

I did indeed view this post & it works to a certain level,
Everything i centered & at 400 pixels wide apart from the text box that you reply or post a new topic.  Click here to view my forum

Ive had a fiddle with the template files but with no luck, i would like the forum to be 400 pixels wide, any ideas
?????