a couple of bits of help on this:
first, you have to consider that many have a smaller resolution, so bringing down the size of the header (maybe down to 900X240?) should bring it up a bit.
im big on joomla, and one of the things that i think is necessary to keep yourself looking professional is to hide traces of the template youre using. just changing the values of the xml files should be enough. this could also help on search engines - as ive experienced jumps just by making it unique.
use your module positions wisely. if you're bringing up another menu on the left hand side, it should be different than the top menu - especially with the lack of content. my opinion is to eliminate the menu altogether and use a small banner or unique content on the left. name the images and descriptions to the keywords you have for the site as well. that'll help later on.
the only other thing is to change up the buttons for the image gallery - you can usually find that in the components folder. i'd personally try to keep it in the same theme color as the rest of the site.
otherwise, its a clean looking site. i like.