What I think you really want is for the text to render in front of the drop shadow, not behind it; this will enhance the illusion. What you need to do is add this to the CSS for the page in the main content frame:
<BLOCKQUOTE><font size="1"face="Geneva, Verdana, Arial">code:</font><HR><pre><font size=1 face=courier>body {
color: black;
background-color: white;
background-image: url(url-of-image);
background-position: top left;
background-repeat: repeat-x; <font color = brown>/* Only repeat horizontally */</font>
background-attachment: fixed; <font color = brown>/* Don't scroll with the page */</font>
}</font>[/code]
This will work for IE4 and up, anything Gecko-based, and Opera 4 and up. NS4 and IE3 will still show the gradient as you intended, but it will scroll with the page (looking like you just put a grey gradient at the top of the page, which isn't quite what you intended but still doesn't look bad).