js图片上下不间断滚动代码

<div id=link_logo style="OVERFLOW: hidden; WIDTH: 282px; HEIGHT: 518px">
<div id=link_logo1 style="OVERFLOW: hidden">
<table width="282"  border="0" cellpadding="10" cellspacing="0">
<tr><td><img src="http://www.jzread.com/skin/default/imga/logo.gif" border="0" width="282" height="76" /></td></tr>
<tr><td><img src="http://www.jzread.com/skin/default/imga/logo.gif" border="0" width="282" height="76" /></td></tr>
<tr><td><img src="http://www.jzread.com/skin/default/imga/logo.gif" border="0" width="282" height="76" /></td></tr>
<tr><td><img src="http://www.jzread.com/skin/default/imga/logo.gif" border="0" width="282" height="76" /></td></tr>
<tr><td><img src="http://www.jzread.com/skin/default/imga/logo.gif" border="0" width="282" height="76" /></td></tr>
<tr><td><img src="http://www.jzread.com/skin/default/imga/logo.gif" border="0" width="282" height="76" /></td></tr>
<tr><td><img src="http://www.jzread.com/skin/default/imga/logo.gif" border="0" width="282" height="76" /></td></tr>
</table> 
</div>
<div id=link_logo2></div>
</div>

<script>
var speed=65
link_logo2.innerHTML=link_logo1.innerHTML
function Marquee2(){
if(link_logo2.offsetTop-link_logo.scrollTop<=0)
link_logo.scrollTop-=link_logo1.offsetHeight
else{
link_logo.scrollTop++
}
}
var MyMar2=setInterval(Marquee2,speed)
link_logo.onmouseover=function() {clearInterval(MyMar2)}
link_logo.onmouseout=function() {MyMar2=setInterval(Marquee2,speed)}
</script>