window.onload = rolloverInit;

function rolloverInit() {
			for (var i=0; i<document.images.length; i++){
			if (document.images[i].parentNode.tagName == "A"){
			setupRollover(document.images[i]);
			}
      }
}
 function setupRollover(thisImage) {
   thisImage.outImage = new Image();
	thisImage.outImage.src = thisImage.src;
	thisImage.onmouseout = rollOut;
	
	thisImage.overImage = new Image();
	thisImage.overImage.src = "images/menu/" + 
	thisImage.id + "_on.png";
	thisImage.onmouseover = rollOver;
	}
	
	 function rollOver() {
	   this.src = this.overImage.src;
	}
	 	function rollOut() {
		  this.src = this.outImage.src;
		  }