Confused about load vs parseXML

Greetings

I am fooling with a gallery, which I need to draw from dynamically created XML. The gallery, however, has the following hard-coded;

if(_root.xmlFile==undefined){
      _root.xmlFile="gallery.xml"
}
imageXML.load(_root.xmlFile);

My first solution was to change this to;

if(_root.xmlFile==undefined){
      _root.xmlFile=(_root.MYVARS)
}
imageXML.load(_root.xmlFile);

Where MYVARS was specified in the URL string:

<param name="movie" value="new1.swf?MYVARS=gallery.xml">

That way I can have the same flash file access many different galleries. However, what I REALLY need is to load the vars right in the embed/object tags, like so;

<param name="movie" value="new1.swf?MYVARS=<gallery>more xml stuff</gallery>">
or
<param name="movie" value="new1.swf"> <PARAM NAME="FlashVars" VALUE="&?MYVARS=<gallery>more xml stuff</gallery>">

However, I have tried to change the gallery actionscript to the following;

if(_root.xmlFile==undefined){
      _root.xmlFile=(_root.MYVARS)
}
imageXML.parseXML(_root.xmlFile);

And this doesn't work. Am I missing something? Help! I'm under the gun to get this working, after a solid day of messing about.