You can try changing wxglobal.php styling to put a bit of padding left/right into the mix.. that will move it more to the middle.
Change <div id="main-copy">
to something like <div style="padding-left: 20%; padding-right: 20%;" id="main-copy">
Tweak the percentages as you like. This will, however, screw up the presentation on the narrow-aspect template, so only use this mod if you have disabled wide/narrow screen select on your site.
Best regards,
Ken