I would change your font. Comic Sans doesn't give off a professional vibe.
I second this. Comic Sans is a graphic designer's nightmare. Try sticking to Arial or Helvetica.
The pixelation around the edges of the navigation links is bad, too. Try recreating the files and saving as PNG. PNG allows for transparency while also letting you have smoother edges.
I'd also lose the image to the right of the header. It clutters up the screen. You may want to change the main image with the rock to an image that better represents the service you're providing.
Also might want to remove the Intuit banner at the bottom:
<div id="footer" style="position:absolute; top: 856px; left: 0px; width: 900px; height: 24px; background-color: #ffffff; text-align: center"><span style="color: #000000; font-size: 12px; font-family: arial; padding-left: 8px"><a target="_blank" href="http://www.intuit.com/website-building-software/">Website Building Software & Website Design Tools</a><a target="_blank" href="http://business.intuit.com"> by Intuit Small Business</a></span></div>