A better solution would probably be to just run one form instead of 2. That way your vars are always filled out on the submit and it doesn't matter if your rewrite them each time.
Code:
<?
include 'header.php';
if (isset($_POST['submit'])) {
$avatar = $_POST["avatar"];
$quote = $_POST["quote"];
$banner = $_POST["banner"];
$sig = $_POST["sig"];
//insert the values
if (!isset($message)){
// kill this write and include it in the next
// $result= mysql_query("UPDATE `grpgusers` SET `avatar`='".$avatar."', `quote`='".$quote."' WHERE `id`='".$user_class->id."'");
$result= mysql_query("UPDATE `grpgusers` SET `banner`='".$banner."', `sig`='".$sig."', avatar`='".$avatar."', `quote`='".$quote."'WHERE `id`='".$user_class->id."'");
echo Message('Your preferences have been saved.');
die();
}
}
?>
<?
if (isset($message)) {
echo Message($message);
}
?>
<tr><td class="contenthead">
Account Preferences
</td></tr>
<tr><td class="contentcontent">
<form name='login' method='post'>
<table width='50%' border='0' align='center' cellpadding='0' cellspacing='0'>
<tr>
<td height='28'><font size='2' face='verdana'>Avatar Image Location </font></td>
<td><font size='2' face='verdana'>
<input type='text' name='avatar' value='<?= $user_class->avatar ?>'>
</font></td>
</tr>
<tr>
<tr>
<td height='28' align="right"><font size='2' face='verdana'>Quote </font></td>
<td><font size='2' face='verdana'>
<input type='text' name='quote' value='<?= $user_class->quote ?>'>
</font></td>
</tr>
<td> </td>
<td><font size='2' face='verdana'>
// kill this submit button here...
<!-- <input type='submit' name='submit' value='Save Preferences'> -->
</font></td>
</tr>
</table>
</form>
<br>
<tr><td class="contenthead">
Add Banner
</td></tr>
<tr><td class="contentcontent">
// kill this form line
<!-- <form name='login' method='post'> -->
<table width='100%' border='0' align='center' cellpadding='0' cellspacing='0'>
<tr>
<td height='28'><font size='2' face='verdana'>Banner Image Location </font></td>
<td><font size='2' face='verdana'>
<input type='text' name='banner' value='<?= $user_class->banner ?>'>
</font></td>
</tr>
<tr>
<tr>
<td height='28' align="right"><font size='2' face='verdana'>Quote </font></td>
<td><font size='2' face='verdana'>
<input type='text' name='sig' value='<?= $user_class->sig ?>'>
</font></td>
</tr>
<td> </td>
<td><font size='2' face='verdana'>
<input type='submit' name='submit' value='Save Preferences'>
</font></td>
</tr>
</table>
</form>
<?
include 'footer.php';
?>