function rollover(){
	var ary = getGroup("img","rollover", null);
	for(var i=0; i<ary.length; i++){
		if(ary[i].src.match(/_on(.gif|.jpg|.png)/i)) continue;
		var img = new Image();
		img.src = ary[i].src.replace(/(.gif|.jpg|.png)/, "_on" + "$1");
		
		ary[i].onmouseover = setMouseover(ary[i].src);
		ary[i].onmouseout = setMouseout(ary[i].src);
	}
}

function setMouseover(objsrc){
	return function(){this.src = this.src.replace(/(.gif|.jpg|.png)/i, "_on" + "$1");}
}
function setMouseout(objsrc){
	return function(){this.src = this.src.replace(/_on(.gif|.jpg|.png)/i, "$1");}
}

function getGroup(tag, cName, oParent){
	var target = oParent;
	if(!target) target = document;
	var tags = target.getElementsByTagName(tag||"*");
	var ary = [];
	
	for(var i=0; i<tags.length; i++){
		if(!cName || tags[i].className == cName)
			ary.push(tags[i]);
	}
	return ary;
}

function addEvent(evnt, func){
	if(window.addEventListener) {
		window.addEventListener(evnt, func, false);
	}
	else if(window.attachEvent) {
		window.attachEvent("on"+evnt, func);
	}
}
	
addEvent("load", rollover);