Need some help with a contect form

<form name="form1" method="post" action="">
<table width="450" border="0">
<tr>
<td width="73">Name</td>
<td width="367"><label>
<input name="name" type="text" id="name">
</label></td>
</tr>
<tr>
<td>Email</td>
<td><label>
<input name="email" type="text" id="email">
</label></td>
</tr>
<tr>
<td>Subject</td>
<td><label>
<input name="subject" type="text" id="subject">
</label></td>
</tr>
<tr>
<td>Message</td>
<td><label>
<textarea name="message" id="message"></textarea>
</label></td>
</tr>
<tr>
<td>&nbsp;</td>
<td><label>
<input name="Submit" type="submit" class="button" value="Send">
<input name="Submit2" type="reset" class="button" value="Clear">
</label></td>
</tr>
</table>
</form>

/* All form fields are automatically passed to the PHP script through the array $HTTP_POST_VARS. */
$name = $HTTP_POST_VARS ['name'];
$email = $HTTP_POST_VARS['email'];
$message = $HTTP_POST_VARS['message'];
$subject = $HTTP_POST_VARS['subject'];


/* PHP form validation: the script checks that the Email field contains a valid email address and the Subject field isn't empty. preg_match performs a regular expression match. It's a very powerful PHP function to validate form fields and other strings - see PHP manual for details. */
if (!preg_match("/\w+([-+.]\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*/", $email)) {
echo "<h4>Invalid email address</h4>";
echo "<a href='javascript:history.back(1);'>Back</a>";
} elseif ($subject == "") {
echo "<h4>No subject</h4>";
echo "<a href='javascript:history.back(1);'>Back</a>";
}

/* Sends the mail and outputs the "Thank you" string if the mail is successfully sent, or the error string otherwise. */
elseif (mail($email,$subject,$message)) {
echo "<h4>Thank you for sending email</h4>";
} else {
echo "<h4>Can't send email to $email</h4>";
}
?>
</body>
</html>