[monolithed]

<form action="" method="post">
    <select>
        <option selected="selected" disabled="disabled">- выберите -</option>
        <option>1</option>
        <option>2</option>
    </select>
</form>
<script type="text/javascript">
window.onload = function(){
    document.getElementsByTagName('select')[0].onchange = function(){
        alert('выбрано: ' + this.options[this.selectedIndex].text);
    };
};
</script>