You could do something like this:-
http://www.wickham43.com/forumposts/...ebs091114.html
CSS
http://www.wickham43.com/forumposts/mystyle.css
I didn't change your Spry menu file and didn't test the menu.
Your Spry menu is width: 63em; which I found is 1008px wide using a default 16px font-size (63*16= 1008). If you use a smaller font size, the width will be less.
As your logo image is 1000px wide and had 3px margins making 1006px, I changed the borders to 4px to tie up with the menu, then the wrapper and all other divs have to add up to 1008px. This is a bit too wide really, as a 1024*768 screen resolution may have a vertical scrollbar of 18px which leaves only 1006px, so you will see a small horizontal scrollbar in some browsers.
It doesn't really matter as long as everything ties up, but mixing ems with px can be difficult so I would resize the menu in px and make the total width 1000px including borders although this will cut off a little bit of the logo.
Your font-families Maiandra GD and amienne probably aren't available on most browsers so you should specify browser-safe fonts as an alternative like I have.
I have used several container divs just to be safe, because I don't know how much content you will have or whether you are going to put some large images in the divs. It may be possible to remove one or two containers.