Help!

look at this page:
http://biography.morrisdees.cjb.net

THere's a DHTML Menu in the header which is Thomas Brattli's Cool Menus 3

and there's some javascript for folders under the navigation section. But it doesn't work in Netscape! Not even Netscape 4.7 They both work individually in Netscape but not together. Is there a way that I can do an IF statement in Javascript so that I only the DHTML Menu is visible in Netscape?

THis is what I had before but it doesn't work. but then again, I'm not a javascript genius.

Code:
<SCRIPT language=javascript>
var browser=navigator.appName

if (browser == "Microsoft Internet Explorer")
{
document.write("
<script src='../files/foldersjs.js'></script><script src='../files/biography.js'></script><script>initializeDocument()</script>");
}
Can someone please help me?
Thank you!