javascript firefox兼容问题

 <div id="rolllink" style="OVERFLOW: hidden; WIDTH: 1004px; HEIGHT: 145px; margin:1px auto">
                <table cellspacing="5" width="100%">                    <tr>
                      <td id="demo11">
                       <div id="rolllink1">
                          <table width="1004px" border=0 align=center cellpadding=0 cellspacing=5 bordercolor="#072AFE">
                         
                              <tr>                                <td align="middle"><a href="#"><img src="image/g-1.gif" border="0"/></a></td>
                                <td align="middle"><a href="#"><img src="image/g-2.gif" border="0"/></a></td>
                                <td align="middle"><a href="#"><img src="image/g-3.gif" border="0"/></a></td>
                                <td align="middle"><a href="#"><img src="image/g-4.gif" border="0"/></a></td>
                                <td align="middle"><a href="#"><img src="image/g-5.gif" border="0"/></a></td>
                                <td align="middle"><a href="#"><img src="image/g-6.gif" border="0"/></a></td>
                              </tr>
                            
                          </table>
                          </div>
                      </td>
                      <td id="demo12" ><div id="rolllink2" ></div></td>
                    </tr>                </table> </div>
              <script language="javascript" type="text/javascript">
//滚动的速度   
var rollspeed=1;

//运行时将rolllink2的值等于rolllink1的值
rolllink2.innerHTML=rolllink1.innerHTML;
function Marquee(){
//如果rolllink滚动的左边位置等于rolllink1的宽度时，说明第一轮滚动完毕,将rolllink的值设为0重新滚动;
if(rolllink.scrollLeft==rolllink1.offsetWidth){
rolllink.scrollLeft=0;
}else{
//否则rolllink左边的值相加，即一直在滚动
rolllink.scrollLeft++;
}
}

//setInterval的功能是根据rollspeed的值设置Marquee函数的执行时间间隔
var MyMar=setInterval(Marquee,rollspeed)
//鼠标进入时不执行Marquee函数
rolllink.onmouseover=function() {clearInterval(MyMar)}
//鼠标移开时执行Marquee函数
rolllink.onmouseout=function() {MyMar=setInterval(Marquee,rollspeed)}
</script>如何修改才能兼容firefox？高人求指教。