function initRollOvers()
{
	if( !document.getElementById )
		return;
	
	var preLoads = new Array();
	var allImages = document.getElementsByTagName('img');
	
	for (var i = 0; i < allImages.length; i++) {
		if (allImages[i].className == 'rollover') {
			var src = allImages[i].getAttribute('src');
			var ftype = src.substring(src.lastIndexOf('.'), src.length);
			var oSrc = src.replace(ftype, '_on' + ftype);
			
			//-- スワップ元、スワップ先画像の登録
			allImages[i].setAttribute('pSrc', src);
			allImages[i].setAttribute('oSrc', oSrc);
			
			//-- イメージのプリロード
			preLoads[i] = new Image();
			preLoads[i].src = oSrc;
			
			//-- イベントの設定
			allImages[i].onmouseover = function(){
				this.setAttribute('src', this.getAttribute('oSrc'));
			}
			allImages[i].onmouseout = function(){
				this.setAttribute('src', this.getAttribute('pSrc'));
			}
		}
	}
}

function addOnload(func)
{
	if( typeof window.addEventListener != "undefined" )
		window.addEventListener("load", func, false);
	else 
		if( typeof window.attachEvent != "undefined" )
			window.attachEvent("onload", func);
		else {
			if (window.onload != null) {
				var oldOnload = window.onload;
				window.onload = function(e){
					oldOnload(e);
					window[func]();
				};
			}
			else 
				window.onload = func;
		}
}

addOnload(initRollOvers);