if($.browser.msie && $.browser.version == 6.0)
  {
    var maxWidth = parseInt($('.viewBigPic img').css('max-width'));
    $('.viewBigPic img').each(function(){
      if ($(this).width() > maxWidth)
        $(this).width(maxWidth);
    });
  }

<script type='text/javascript'>
function setPhotoSize(elem, width, height) {
<!--[if IE 6]>
try{
var image=new Image();
image.src=elem.src;
if(image.width>0 && image.height>0){
var rate = (width/image.width < height/image.height)? width/image.width : height/image.height;
if(rate <= 1){
elem.width = image.width*rate;
elem.height = image.height*rate;
}
else {
elem.width = image.width;
elem.height = image.height;
}
}
}catch(e){}
<!--[endif]-->
}
</script>

<div class="viewBigBox">
            <div class="viewBigPic">
            <p><img id="imgid" onload="setPhotoSize(this,730,470)" src="images/viewShow.jpg" alt=""/></p>
            </div>
           </div>

.viewBigBox{ border:1px solid #e3e3e3; background-color:#ffffff; padding:1px;  margin-top:18px;}
.viewBigPic{ background-color:#f7f7f7;padding:20px 14px;}
.viewBigPic p{display:table-cell;width:730px; line-height:470px; overflow:hidden; vertical-align:middle; text-align:center; height:470px;*font-size:390px;}

//實現圖片垂直居中，主要運用了font-size與height的比例
.viewBigPic p img{ vertical-align:middle; max-height:470px; max-width:730px;}