[bes]

<select 
  onchange = "
    var index = this.selectedIndex; 
    var value = this.options[index].value; 
    if (index == 1) {
      myDiv.innerHTML = '<img src='+value+'>'
    } else if (index != 0) {
      var win = window.open(value,'','blank');
    }
"> 
  <option>choose picture</option>
  <option value="http://javascript.ru/forum/image.php?u=19820&dateline=1334914235">1</option> 
  <option value="http://javascript.ru/forum/image.php?u=19820&dateline=1334914235">2</option> 
  <option value="http://javascript.ru/forum/images/ca_serenity/misc/logo.gif">3</option> 
</select> 

<div id="myDiv">
</div>