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Just basing this off looking at the page you could add a div around all of it and give that div your fixed width and center it. Haven't tried it though to know if anything else may cause an issue.
 
Yes, create a div that will hold all the content of the page, as a container ... give it auto left and right margins and everything will be centered.
 
Could just...

HTML:
body {width:960px;
      margin:0 auto;
     }

...surely?

Substitute 960px with the width you want.
 
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