求救！急需一个菜单式的代码更改。

我有一个这样的代码，一个菜单导航，现在要改成：默认的一个菜单(A)是打开的。另一个(B)是关闭的，如下面的代码。点击B后，A收缩回去，B展开。请问怎么改。现在没有分了。以后给补上，谢谢各位了。页面：代码。
<TABLE cellSpacing=0 cellPadding=0 width=158 align=center>
        <TBODY>
        <TR style="CURSOR: hand">
            <TD class=menu_title id=menuTitle1 onMouseOver="this.className='menu_title2';" onClick="menuChange(menu1,60,menuTitle1);" onMouseOut="this.className='menu_title';" background="images/menu/menuup.gif" height=25 style="font-size:12px;"><SPAN>网站常规设置</SPAN> </TD>
          </TR>
        <TR>
          <TD>
            <DIV class=sec_menu id=menu1 style="DISPLAY: none; FILTER: alpha(Opacity=0); WIDTH: 158px; HEIGHT: 0px">
       <TABLE style="POSITION: relative; top: 10px;" cellSpacing=0 cellPadding=0 width=135 align=center>
        <TBODY>
          <tr> 
            <td height="20"><img src="images/menu/bullet.gif" width="15" height="20" border="0" align="absmiddle"><a href="./index.jsp"  target=_parent style="font-size:12px;">返回首页</a></td>
          </tr>
          <tr> 
            <td height="20"><img src="images/menu/bullet.gif" width="15" height="20" border="0" align="absmiddle"><a href="admin/quit.jsp" target="_parent" style="font-size:12px;">注销登陆</a></td>
          </tr>
            </TBODY>
              </TABLE>
            </DIV></TD></TR></TBODY></TABLE>


     <TABLE cellSpacing=0 cellPadding=0 width=158 align=center>
        <TBODY>
        <TR style="CURSOR: hand">
            <TD class=menu_title id=menuTitle2 onMouseOver="this.className='menu_title2';" onClick="menuChange(menu2,60,menuTitle2);" onMouseOut="this.className='menu_title';" background="images/menu/menuup.gif" height=25 style="font-size:12px;"><SPAN>网站栏目管理</SPAN> </TD>
       </TR>
        <TR>
          <TD>
            <DIV class=sec_menu id=menu2 style="DISPLAY: none; FILTER: alpha(Opacity=0); WIDTH: 158px; HEIGHT: 0px">
       <TABLE style="POSITION: relative; top: 10px;" cellSpacing=0 cellPadding=0 width=135 align=center>
        <TBODY>
       <tr>
            <td height="20"><img src="images/menu/bullet.gif" width="15" height="20" border="0" align="absmiddle"><a href="admin/models/modelcount.jsp" target="right" style="font-size:12px;">栏目统计</a></td>
          </tr>
<tr>
 <td height="20"><img src="images/menu/bullet.gif" width="15" height="20" border="0" align="absmiddle"><a href="admin/models/seeModels.jsp" target="right" style="font-size:12px;">栏目浏览</a></td>
          </tr>    
                    </TBODY>
              </TABLE>
            </DIV></TD></TR></TBODY></TABLE>
            
   <script language="javascript">
  var whichOpen="";
  var whichContinue='';
function menuShow(obj,maxh,obj2)//显示框
{
  if(obj.style.pixelHeight<maxh)
  {
    obj.style.pixelHeight+=maxh/20;
obj.filters.alpha.opacity+=5;
obj2.background="";
    if(obj.style.pixelHeight==maxh/10)
  obj.style.display='block';
myObj=obj;
myMaxh=maxh;
myObj2=obj2;
setTimeout('menuShow(myObj,myMaxh,myObj2)','5');
  }
}
function menuHide(obj,maxh,obj2)//隐藏框
{
  if(obj.style.pixelHeight>0)
  {
    if(obj.style.pixelHeight==maxh/20)
  obj.style.display='none';
    obj.style.pixelHeight-=maxh/20;
obj.filters.alpha.opacity-=5;
obj2.background="";
myObj=obj;
myMaxh=maxh
myObj2=obj2;
setTimeout('menuHide(myObj,myMaxh,myObj2)','5');
  }
  else
    if(whichContinue)
  whichContinue.click();
}
function menuChange(obj,maxh,obj2)
{

  if(obj.style.pixelHeight)
  {
    menuHide(obj,maxh,obj2);
whichOpen='';
whichcontinue='';
  }
  else
    if(whichOpen)
{
  whichContinue=obj2;
      whichOpen.click();
}
else
{
  menuShow(obj,maxh,obj2);
  whichOpen=obj2;
  whichContinue='';
}
}
</script>