Pages now expanding to screen width

Hope you can help, can anybody see why these product pages are expanding to screen width. ex http://www.polymate.com.au/7x4onroad.html

Before that, don't you know why using tables for making layout is very bad (http://www.hotdesign.com/seybold/)?

Thanks for replying, agreed I understand but this site has been up for a few years now. They just asked for some minor tweaking and are not interested in having it redone. Is there something I can do to stop the pages expanding, this was not happening before.