Removing Possible Redundant Loads

I am using a neat postload script to load a bunch of images into the user's cache after the page has fully loaded, and I have a quick question

<script type="text/javascript">
//<![CDATA[
function postLoad(){
if(!window.name.match(/preLoad.complete/gi)){
var images = new Array('img/EnglishOn.gif',
'img/EnterOn.gif',
'img/EntrerOn.gif',
'img/FrenchOn.gif',
'img/butt_1_blank.gif',
'img/butt_1_red.gif');


var loader = new Array();
for(var i=0; i<images.length; i++){
loader[i] = new Image();
loader[i].src = images[i];
}
window.name = 'preLoad.complete'
}
}
//]]>
</script>

Can this script be modified to check whether an image has already been loaded, and if so, not reload it? I ask because I may have a long list of images and if the user navigates to another page I would like the script to not re-download X number of images Code: