I'm not sure exactly where the problem is, but I'd start by looking at places within your code where you specify width in your table as pixels instead of percentage. For example, this:
PHP Code:
<img src="tpl_img/bar_middle.gif" height="16" width="100.00" alt="">
There are two places I see with code similar to the above. Also, there's this:
PHP Code:
<img src="../../images/achtergrond.jpg" width="800"
I'm not sure just what part of the page that is, but if you're going to use pixels instead of percent that should be no more than 780. In a browser with 800 x 600 resolution, 10 pixels on each side get chopped off so 780 should prevent horizontal scrolling - provided there isn't something else that I missed in scrutinizing your code.
Something else to consider. Percentage is the preferred method, in my opinion, because the page will render better in different resolution browsers that way.
Hope this helps.