var isDOM=document.getElementById?1:0;
var isIE=document.all?1:0;
var isNS4=navigator.appName=='Netscape'&&!isDOM?1:0;

var preloaded = new Array(); 
 function preload_images() { 
     for (var i = 0; i < arguments.length; i++){ 
         preloaded[i] = document.createElement('img'); 
         preloaded[i].setAttribute('src',arguments[i]); 
     }; 
 }; 
 
preload_images( 
	 'images/bajar-subtitulo.gif',
	 'images/bajar-subtitulo-on.gif' 
 );