下拉菜单友情链接

<form>
<select onchange="window.open(this.options[selectedIndex].value,'','');" name="menu1" size="1">????????????
?<option>友情链接</option>
?<option value="www.baidu.com">百度</option>???
??????? <option value="www.sina.com.cn">新浪</option>?????
</select>
</form>?