Your "http://www.avavenue.com/Images/GradientBackground.png" should be 1 pixel wide, and in your CSS you can do:
background: url('GradientBackground.png') repeat-x top;
That will save you a lot of bandwidth, as the image is 2MB at the moment.
Also, like SB65 said, use a doctype, it will make it more consistent with chrome/firefox:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">