I know your thread is kinda old but I worked this up anyways.

You can try it out here using the following url:
http://inputout.org/sandbox/dropdown.php

the url will accept 'd', 'm', and 'y' as parameters
ex: http://inputout.org/sandbox/dropdown...27&m=04&y=1978

will display 27, April, 1978 in the select boxes
if nothing is passed, it will default to 1, 01, 1960

you would of course, replace the GETs with the values from your database or some POST results

hope this helps.

PHP Code: 
<html>
<title>Dropdown Selecta</title>
<body>

<?php
$postedDay = isset($_GET['d']) ? (int)$_GET['d'] : 1;
$postedMonth = isset($_GET['m']) ? (int)$_GET['m'] : 01;
$postedYear = isset($_GET['y']) ? (int)$_GET['y'] : 1960;
?>

<select name="day" id="day" class="textfield validate-selection required">
    <?php
        $days = range(1,31);
        foreach ($days as $day) { ?>
            <option value="<?php echo $day; ?>"<?php echo $day == $postedDay ? " selected=\"selected\"" : ""; ?>><?php echo $day; ?></option>
    <?php } ?>
</select>

<select name="month" id="month" class="textfield validate-selection required">
    <?php
        $months = array('01'=>'Jan', '02'=>'Feb', '03'=>'Mar', '04'=>'Apr', '05'=>'May', '06'=>'Jun', '07'=>'Jul', '08'=>'Aug', '09'=>'Sep', '10'=>'Oct', '11'=>'Nov', '12'=>'Dec');
        foreach ($months as $key=>$value) { ?>
            <option value="<?php echo $key; ?>"<?php echo $key == $postedMonth ? " selected=\"selected\"" : ""; ?>><?php echo $value; ?></option>
        <?php } ?>
</select>

<select name="year" id="year" class="textfield validate-selection required">
    <?php
        $years = range('1960', '2012');
        foreach ($years as $year) {?>
            <option value="<?php echo $year; ?>"<?php echo $year == $postedYear ? " selected =\"selected\"" : ""; ?>><?php echo $year; ?></option>
    <?php } ?>
</select>

</body>
</html>