Jquery .load() with data from form

I am trying to load a page into a modal window "checkout.php" after submitting a form, but I need it to load with the results of the form. Normally, one would just set the action of the form to the url and the data gets passed, but in this case, the page needs to be loaded into a modal with that data which requires the use of more jQuery than I know.

HTML

<form id="shippingform" name="shippingform" method="post" action="#">
<table id="box-table-a" width="25%" border="1">
<thead>
    <tr>
        <th scope="col" width="40%">USPS Option</th>
        <th scope="col" width="40%">Price</th>
        <th scope="col" width="20%" style="text-align: right;">Select</th>
    </tr>
</thead>
<tbody>
<tr>
  <td class="first">Ground:</td>
  <td><?php echo "$" . sprintf("%01.2f", $groundTotal) ?></td>
  <td class="last"><input name="shipping" type="radio" id="radio" value="<?php echo $groundTotal ?>" checked="checked" /></td>
</tr>
<tr>
  <td class="first">Priority:</td>
  <td><?php echo "$" . sprintf("%01.2f", $priorityTotal) ?></td>
  <td class="last"><input type="radio" name="shipping" id="radio2" value="<?php echo $priorityTotal ?>" /></td>
</tr>
<tr>
  <td class="first">Express:</td>
  <td><?php echo "$" . sprintf("%01.2f", $expressTotal) ?></td>
  <td class="last"><input type="radio" name="shipping" id="radio3" value="<?php echo $expressTotal ?>" /></td>
</tr>
</tbody>
</table>
<a href="#" onclick="totalCalc()">submit</a>
</form>

JS

<script language="javascript">
function totalCalc() {
$('#cartdialog').load("/ash/shop/checkout.php");
}
</script>

What I have above will load the checkout.p