<input type="hidden" name="***" id="script1" value="" />
<select id="script1_1" onchange="rassa()">   
<option value="0">Выберите расу</option>    
<option value="01">1</option>    
<option value="02">2</option>    
<option value="03">3</option>    
<option value="04">4</option>   
<option value="05">5</option>   
</select>  

<img id="clanImage" src="/rasa/01.png">
<script>
function rassa() {
    var q = $('#script1_1').val();
    $('#clanImage').attr('src', '/rasa/'+q+'.png');
    $('#script1').val(q);
}
</script>