[jQuery] Ajax Form Plugin not posting variables in IE7/8--Empty $_POST array, but works in all other browsers

[PEP]

Hello,

I've created an extremely simple price calculator form using the form
plugin (http://malsup.com/jquery/form/), that sends some dimensions to
a php script, which then reports the correct price back after some
calculations into a div using ajaxForm.  This is working in FF,
Chrome, and Safari perfectly, but in IE 7/8, the form variables are
not being posted for some reason--the server-side script executes, but
the $_POST array is empty.  If I turn off javascript in IE, the form
submits the usual way, and the correct values are calculated.  This is
driving me insane.  Below is my script and form HTML:

<script type="text/javascript">
// prepare the form when the DOM is ready
$(document).ready(function() {
    // bind form using ajaxForm
    $('#quote').ajaxForm({
        // target identifies the element(s) to update with the server
response
       target: '#output',

        // success identifies the function to invoke when the server
response
        // has been received; here we apply a fade-in effect to the
new content
        success: function() {
            $('#output').fadeIn('slow');
        }
    });
});
</script>

<div class="container">
<h4>Price Quote Calculator</h4>
<form name="quote" id="quote" method="POST" enctype="application/x-www-
form-urlencoded" action="quote.php">
<label for="vendor">
Select a vendor:
</label>
<select id="vendor" name="vendor">
<option value="vendor1">vendor1</option>
<option value="vendor2">vendor2</option>
<option value="vendor3">vendor3</option>
</select>

<label for="width">
Select Width:
</label>
<select id="width" name="width">
<option value="1">1 in</option>
<option value="2">2 in</option>
<option value="3">3 in</option>
<option value="4">4 in</option>
<option value="5">5 in</option>
</select>

<label for="length">
Select Length:
</label>
<select id="length" name="length">
<option value="1">1 in</option>
<option value="2">2 in</option>
<option value="3">3 in</option>
<option value="4">4 in</option>
<option value="5">5 in</option>
</select>

<input type="submit" value="Get Quote!" />
</form>
<div id="output"></div>
</div><!--end div "container"-->

Am I missing something obvious (a very real possibility)?  Thank you
in advance for any help you offer.
--Paul