Drop Down Menu Position

I have a drop down menu that has a one level submenu on 5 drop downs, that is written javascript. I works great except for the positioning of it on the window. When the Internet Window is expanded, resized the menu moves on me. I need the menu always centered on the page since the page itself is a centered table.

Currently the positons of the main header menus and the submenus are based on absolute positions (I modified an old one). When I change it to relative function I can get the main header menus to work fine, but when I change the submenus, it moves the rest of the page down. Its like it is expanding the header. (The menu is linked into a header html. Then that header.html is linked to each page.)

Is there anyway to insert the entire menu into a table, position that table by relative, then have the menu absolute positons work off that table instead of the IE window. Or is there a better option to get this menu centered on the page?

Here is a link to the javascript code:
[url]http://www.cityofhastings.org/test2/common/main_menu.js[/url]

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