function preLoadImages(){
var t='<layer top="-100" left="0" visibility="hide"><div style="position:absolute; top:-100px; left:0px; visibility:hidden">';
for(i=0;i<arguments.length;i++)t+='<img src="'+arguments[i]+'" height="10" width="10">';
t+='<\/div><\/layer>';
document.write(t);
}

preLoadImages('nav01Over.jpg','nav02Over.jpg','nav03Over.jpg','nav04Over.jpg','nav05Over.jpg','nav06Over.jpg','nav01.jpg','nav02.jpg','nav03.jpg','nav04.jpg','nav05.jpg','nav06.jpg'); 

function swapImage(imgN,imgU){
if(document.images)document.images[imgN].src=imgU;
}