如何控制同一个页面下两个区域滚动

这几天一直在研究这个问题——区域滚动代码怎么才可以在同一个页面同时使用面不影响。
问题是这样的，我想用代码来控制两个iframe页面竖向滚动，两个相互不影响。就是我在控制左边iframe时，右边iframe不动，控制右边iframe时，左边iframe不动。
代码是这样的
<table width="510" border="0" align="center" cellpadding="0" cellspacing="0" class="solid-top solid-bottom">
  
  <tr>
    <td width="480"><iframe src="news-1.htm" name="new_date" 
                                width="480" marginwidth="0" height="150"
                                marginheight="0" scrolling="No" 
                                frameborder="0" id="new_date" border="0" framespacing="2" 
                                noresize="noresize" vspale="0"></iframe></td>
    <td width="30" align="center" valign="top"><br>
        <img src="images/scrollup.gif" alt="点住不放可以快速向上滚动" 
                                width="11" height="11" vspace="5" class="opacity" 
                                onMouseDown="movover();movstar(-3,2)" 
                                onMouseUp="movover();movstar(-1,20)" 
                                onMouseOver="movstar(-1,20);o_down(this)" 
                                onMouseOut="movover();o_up(this)" /><br>
        <img src="images/scrolldw.gif" alt="点住不放可以快速向下滚动" 
                                width="11" height="11" vspace="5" class="opacity" 
                                onMouseDown="movover();movstar(3,2)" 
                                onMouseUp="movover();movstar(1,20)" 
                                onMouseOver="movstar(1,20);o_down(this)" 
                                onMouseOut="movover();o_up(this)" /> <br>
    <script language=JavaScript>
function movstar(a,time){
movx=setInterval("mov("+a+")",time)
}
function movover(){
clearInterval(movx)
}
function mov(a){
scrollx=new_date.document.body.scrollLeft
scrolly=new_date.document.body.scrollTop
scrolly=scrolly+a
new_date.window.scroll(scrollx,scrolly)
}
function o_down(theobject){
object=theobject
while(object.filters.alpha.opacity>60){
object.filters.alpha.opacity+=-10}
}
function o_up(theobject){
object=theobject
while(object.filters.alpha.opacity<100){
object.filters.alpha.opacity+=10}
}
function wback(){
if(new_date.history.length==0){window.history.back()}
else{new_date.history.back()}
}
        </script></td>
  </tr>
</table>请高手指点迷津