you problem is that your table you have the background in. Doesnt go behind the navigation. Dreamweavers preview window isnt very accurate to be honest. I wouldnt recomend using it.
This is what i got:
All did was delete that table you have containing the header image.
And add this to your css:
If you still want to keep that table. Just remove the background image from it, and make it 190 height, not 200Code:#header { height:190px; width:100%; background:url(../header.png); }