First time javascript user here, I hope this isn't an incredibly stupid question. I am trying to validate a form using javascript and have managed to get it to work when checking for blank fields and invalid email addresses, but I cannot for the life of me figure out how to validate a pull down menu. My menu displays with Select Age followed by the options, but I want to ensure that the user actually does select their age. I have included my javascript and the menu section from my form in case that matters. I've been googling and trying snippets but none of them seem to work. Any help would be greatly appreciated :)

<script language="javascript" type="text/javascript">
<!--
function verify(form) {
if (form["firstname"].value == '') {
alert("Please enter your first name");
return false;
}
if (form["surname"].value == '') {
alert("Please enter your surname");
return false;
}
if (form["address"].value == '') {
alert("Please enter your address");
return false;
}
if (form["email"].value == '') {
alert("Please enter your email address");
return false;
}


var j = new RegExp();
j.compile("@");
if (!j.test(form["email"].value)) {
alert("You must supply a valid email address.");
return false;
}
return true;

}
//-->

</script>



<select id="age" name="age">
<option value="0" selected="selected">Select Age</option>
<option value="0-17">0-17</option>
<option value="18-35">18-35</option>
<option value="36-55">36-55</option>
<option value="55+">55+</option>
</select>