function initRollovers(){
	if(!document.getElementById) return
	var aPreLoad = new Array();
	var sTempSrc;
	var aImages = document.getElementsByTagName('img');
	
	for(var i=0;i<aImages.length;i++){
		if(aImages[i].className=='imgover'){
			var src = aImages[i].getAttribute('src');
			var ftype = src.substring(src.lastIndexOf('.'), src.length);
			//var hsrc = src.replace(ftype, '_ov'+ftype);
			var hsrc = src.replace(/_on\./,".").replace(ftype, '_ov'+ftype);
			aImages[i].setAttribute('hsrc', hsrc);
			aPreLoad[i] = new Image();
			aPreLoad[i].src = hsrc;
			aImages[i].onmouseover = function(){
				sTempSrc = this.getAttribute('src');
				if(this.getAttribute('src').indexOf('_on')<0) this.setAttribute('src', this.getAttribute('hsrc'));
			};
			aImages[i].onmouseout = function(){
				if(!sTempSrc) sTempSrc = this.getAttribute('src').replace('_ov'+ftype, ftype);
				if(this.getAttribute('src').indexOf('_on')<0) this.setAttribute('src', sTempSrc);
			}
		}
	}
}

if(window.addEventListener){  /* Firefox,Safari,Opera */  
	window.addEventListener("load", initRollovers, false);  
}else if(window.attachEvent){  /* IE4, IE5, IE6, IE7 */  
	window.attachEvent("onload", initRollovers);  
}else if (document.getElementById || document.all) { /* その他DOM準拠 */  
	window.onload = initRollovers;  
}