function rollover(imgObj) {
	var oldSrc = imgObj.src;
	var ext = oldSrc.substring(oldSrc.lastIndexOf("."), oldSrc.length);
	imgObj.src = oldSrc.substring(0, oldSrc.lastIndexOf(".")) + "_over" + ext;
	if (!imgObj.onmouseout) {
		imgObj.onmouseout = function() {
			rolloff(imgObj);
		}
	}
}

function rolloff(imgObj) {
	var oldSrc = imgObj.src;
	var ext = oldSrc.substring(oldSrc.lastIndexOf("."), oldSrc.length);
	imgObj.src = oldSrc.substring(0, oldSrc.lastIndexOf("_")) + ext;
}

function preloadImages() {
  var d=document; 
  if(d.images)
  { 
  	if(!d.preload) 
  	{
  		d.preload=new Array();
  	}
    var i,j=d.preload.length,a=preloadImages.arguments; 
    for(i=0; i<a.length; i++)
    if (a[i].indexOf("#")!=0){ 
    	d.preload[j]=new Image; d.preload[j++].src=a[i];}
    }
}