I have no idea why this wont work - simple UPDATE

Hi Guys, been working on this for ages, its driving me nuts and wasting my time as I need to move on to other things...

If I echo the query after hitting submit, i get everything through except the id, which of course renders the query useless as it wont update without it. I tried using $_GET['id'] in the query (as it is being passed through a URL and it wont work, however if I echo the $_GET['id'] in the page, the id is displayed.  I have tried setting the $_GET['id'] into a hidden form field and set the query to WHERE id = $_POST['id'] and have tried putting the $_GET['id']into a variable (i think thats what its called) as $id and used that, but nothing... as i said i can echo these on the page, but they are not existing in the query.... heres my code (all of it, so i hope i can get this fixed)...

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<?php
ob_start();

include('admin_functions.php');

db_connect(); // function which just connects - db connection status is not an issue.

$query_pplay = "SELECT * FROM products WHERE id = '{$_GET['id']}'";
$pplay = mysql_query($query_pplay) or die(mysql_error());
$row_pplay = mysql_fetch_assoc($pplay);

$query_pplay2 = "SELECT * FROM cats WHERE id = '{$row_pplay['cat_id']}'";
$pplay2 = mysql_query($query_pplay2) or die(mysql_error());
$row_pplay2 = mysql_fetch_assoc($pplay2);

$query_pplay3 = "SELECT DISTINCT * FROM cats ORDER BY title";
$pplay3 = mysql_query($query_pplay3) or die(mysql_error());
$row_pplay3 = mysql_fetch_assoc($pplay3);

if (count($_FILES) > 0 and array_key_exists('image', $_FILES)) {
                        if (is_uploaded_file($_FILES['image']['tmp_name'])) {
                                                if ($_FILES['image']['name'] != '') {
                                                                        $pic_name = "1_" . date("d_m_Y_H_i") . "_" . $_FILES['image']['name'];
                                                } else {
                                                                        exit; //Can't really do anything if we don't have a filename
                                                }
                                                $uploaddir = '../images/parts/';
                                                $thumbnaildir = '../images/parts/thumbs/';
                                                $sourcefile = $uploaddir . $pic_name;
                                                move_uploaded_file($_FILES['image']['tmp_name'], $sourcefile);
                                                $pdestfile = "{$thumbnaildir}tn_{$pic_name}";

                                                $g_imgcomp = 50;
                                                $psize = 150;
                                                resampimagejpg($psize, $sourcefile, $pdestfile, $g_imgcomp);
                        }
}

$p_title = addslashes($_POST['title']);
$p_desc = addslashes($_POST['description']);
$p_cat_id = addslashes($_POST['cat_id']);
$p_price = addslashes($_POST['price']);

$s_title = stripslashes($row_pplay['title']);
$s_description = stripslashes($row_pplay['description']);
$s_cat_id = stripslashes($row_pplay['cat_id']);
$s_price = stripslashes($row_pplay['price']);

if (isset($_POST['submit'])) {
if ($_FILES['image']['name'] != '') {
                                                $updateSQL = "UPDATE products SET title='{$p_title}', description='{$p_desc}', cat_id='{$p_cat_id}', price='{$p_price}', image='{$pic_name}' WHERE id = '{$row_pplay['id']}'";
                        } else {
                                                $updateSQL = "UPDATE products SET title='{$p_title}', description='{$p_desc}', cat_id='{$p_cat_id}', price='{$p_price}' WHERE id = '{$row_pplay['id']}'";
                        }
                        $Result1 = mysql_query($updateSQL) or die(mysql_error());
                        echo $updateSQL ;
//                        header("Location: index.php?goto=thanks");
}

echo '
<div id="content">
<form method="post" name="form1" action="prod_edit.php" enctype="multipart/form-data">
<table width="400" border="0">
<tr>
<td width="100">Title:</td>
<td><input class="formfield" type="text" name="title" value="' . $s_title . '" size="32"></td>
</tr>
<tr>
<td width="100">Description:</td>
<td><textarea class="formfield" name="description" cols="100" rows="15">' . $s_description . '</textarea></td>
</tr>
<tr>
<td width="100">In Category:</td>
<td><select name="cat_id">
<option value="' . $row_pplay2['id'] . '">' . $row_pplay2['title'] . '</option>';
do {
                        echo '<option value="' . $row_pplay3['id'] . '">' . $row_pplay3['title'] . '</option>';
} while ($row_pplay3 = mysql_fetch_assoc($pplay3));
echo '
</select></td>
</tr>
<tr>
<td width="100">Price:</td>
<td><input class="formfield" type="text" name="price" value="' . $s_price . '" size="32"></td>
</tr>
<tr>
<td width="100">Image:</td>';
if ($row_pplay['image'] == true) {
                        echo '<td><a href="../images/parts/' . $row_pplay['image'] . '" target="_blank"><img src="../images/parts/thumbs/tn_' . $row_pplay['image'] . '" border="0"/></a><br />Upload new Image:<br /><input type="file" name="image" class="formfield"></td>';
} else if ($row_pplay['image'] == false) {
                        echo '<td><input type="file" name="image" class="formfield"></td>';
}
echo '
</tr>
<tr>
<td width="100"><input class="formsubmit" type="submit" name="submit" value="Update Record" /></td>
<td><input type="reset" class="formsubmit" name="reset" value="Clear Form" /></td>
</tr>
</table>
<form type="hidden" name="id" value="'.$_row_pplay['id'].'">
</form>
</div>';

mysql_close();

?>
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Thanks Guys! :)

Christian