Why don't you make the table have the scrollbar rather than making the page about 500% wide?
Wrap the table in a div and apply this css:
This keeps the table in view and allows for the table to scroll while the page is unaffected. As the table is almost most of the screen width anyway there's not much difference to having the scrollbar on the table rather than on the whole page which wrecks the layout.
Otherwise you will need to put your header and footer back in the flow and take out the absolute positioning and also any widths set in those elements so that the page expands to max. (But a 500% (approx) wide page will look very odd, which is why I recommend scrolling the table instead).