You don't use
mailto:, that will just open up the users default email client like Outlook Express. You would need a php script that would insert the data into a database.
Your form would look like this (copy and pasted your source, changed action and names/id's).
CODE
<form action="mail.php" method="post" enctype="text/plain" name="form1" id="form1">
<table width="90%" border="0" cellspacing="2" cellpadding="4" align="center">
<tr>
<td colspan="2" style="vertical-align: top" class="TitleColor">
<label for="name">Name: </label>
<input id="name" name="name" type="text" size="50" /> </td>
</tr>
<tr>
<td colspan="2" style="vertical-align: top" class="TitleColor">
<label for="email">Email: </label>
<input id="email" name="email" type="text" size="50" /> </td>
</tr>
<tr>
<td colspan="2" style="vertical-align: top" class="TitleColor">
<label for="subject">Subject:</label>
<input id="subject" name="subject" type="text" size="50" /> </td>
</tr>
<tr>
<td colspan="2" style="vertical-align: top" class="TitleColor">
<label for="message">Message:</label>
<br />
<br />
<textarea id="message" name="message" rows="5" cols="50"></textarea> </td>
</tr>
<tr>
<td colspan="2">
<input type="submit" name="Submit" value="Send" /> </td>
</tr>
</table>
and then you would have on mail.php a script that inserted the textfields into a database. E.g (don't use this basic and no protection).
CODE
<?php
$name = $_POST['name'];
$email = $_POST['number'];
$subject = $_POST['subject'];
$message = $_POST['message'];
$sql = "INSERT INTO mail".
" (name,email,subject,message) ".
" VALUES('$name','$email','$subject','$message')";
?>
and on another page just echo out the data in the database. You could as you said have it send to your forum private messenger.