Rather than have that top image as a background image, I would at least chop it off from the rest of the background and create a top header div 1280px wide and place the image inside that div and wrap a link around it.
It's a shame to have all those words in an image, though, as it makes them inaccessible. At least include the essential info in your image's alt attribute.
With the remaining background image just a plain color, you can make it much smaller (or just use acolor value) and fill the entire background with that color, which would look much better on big screen anyway.
BTW, your image slider further down is somewhat broken. You need to change the width here:
width: 637px; <font color='"Red"'>/* change to 495px */</font>