body border, how can I set it to 800px

[Kungfu]

clear:both to get that "break"

or clear:left, clear:right. try that.

Also i dont know if your forum is a fixed or fluid. Sounds fixed, but for fluid you can use min-width and in IE its different, i would have to look it up again as its a little function.

You can put some div tag somewhere like <div id="spacer"></div>

Then css

#spacer{
clear:both;
}
or

<div style="clear:both;"></div>