Did you set the size on both the header and headerimg?
#header { margin: 0 !important; margin: 0 0 0 1px; padding: 1px; height: 206px; width: 750px; }
#headerimg { margin: 7px 9px 0; height: 192px; width: 740px; }
Because at the top of the Body there actually are two divs...
<div id="header">
<div id="headerimg">
Also, I think you want to comment out the line that says...
#headerimg { background: url('http://www.pornomagnet.com/wp-content/themes/magnet/images/personalheader.jpg') no-repeat top;}
Feel free to hit me on icq if you want.
Simon