I would do two things here to really improve the looks and performance of the site.
1) Set it so that when the page initially loads, all of the buttons on the left come up at once, rather than as they are actually loaded. Will make it look much cleaner. There's even a way to make the entire site load, before anything is displayed.
2) Use iframes for each page. Currently, as you navigate from page to page using the buttons on the left, the entire left menu reloads from scratch as does the top and a few other things. You could make it never reload that stuff (which is always the same anyway), and only that middle window would have to reload. I think it would make a signifigant improvement. If you need help, or more specifics, let me know.