Nice looking site!
You've got a clean layout, great colors and everything is easy to find.
I'd suggest adding an underline to the links in the nave menu though. Just make it visible on a mouseover.
Aside from that, you might want to spiff up your "About Us" page. The text is pretty sketchy and doesn't read well, take an opportunity to add a descriptive paragraph or two with some more information suggesting why users should shop at your site.
Here's a great article from Jacob Nielsen.
"About Us" -- Presenting Information About an Organization on Its Website (Jakob Nielsen's Alertbox)