2초마다 이미지 바뀌는 스크립트

<SCRIPT LANGUAGE="JavaScript">
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src = ["", "이미지2", "이미지3", "이미지4"]
url = ["링크1", "링크2", "링크3", "링크4"]
duration = 2; //초ads=[]; ct=0;
function switchAd() {
var n=(ct+1)%src.length;
if (ads[n] && (ads[n].complete || ads[n].complete==null))
{
document["Ad_Image"].src = ads[ct=n].src;
}
ads[n=(ct+1)%src.length] = new Image;
ads[n].src = src[n];
setTimeout("switchAd()",duration*1000);
}
function doLink(){
location.href = url[ct];
} onload = function(){
if (document.images)
switchAd();
}
//-->
</SCRIPT>

<A HREF="javascript:doLink();" onMouseOver="status=url[ct];return true;"  onMouseOut="status=''">
<IMG NAME="Ad_Image" SRC="이미지1" BORDER=0></A>