<style type="text/css">
div{
    float:left;
    margin-left:10px;
}
#pict{
    display:none;
}
</style>

<script type="text/javascript">
function chng(s){
    if(s.value==1){
        document.getElementById("pict").style.display="block";
        document.getElementById("pic").src="zdjecie_chlopaka.jpg";
    }else if(s.value==2){
         document.getElementById("pict").style.display="block";
         document.getElementById("pic").src="zdjecie_dziewczyny.jpg";
    }
}
</script>

[HTML] pobierz, plaintext 
<div>
    <select id="p" onchange="chng(this)">
        <option value="1">chlopak</option>
        <option value="2">girl</option>
    </select>
</div>
<div id="pict">
    <img id="pic">
</div>
[HTML] pobierz, plaintext