鼠标放上去图片切换效果

鼠标放上去图片变化
  <script language="javascript">
  function changeImg(obImg,sNewURL)
  {
       if(sNewURL!="") obImg.src=sNewURL;
  }
 
  function preLoad(sURL)
  {
       if(sURL!="")
      {
           var obImg=new Image();
           obImg.src=sURL;
      }
}
preLoad("图片地址");
preLoad("图片地址");
</script>
<img style="cursor:hand;" src="图片地址" border="0" width="50" height="30" onmouseover="changeImg(this,'图片地址');" onmouseout="changeImg(this,'图片地址');">