scripting website in PHP to send e mails?

[Mr E]

ii'm trying to send out 2 e mails from a form. one will be sent to the web administrator the other to a user, however before i even get anywhere i have this error message

Warning: mail() [function.mail]: SMTP server response: 553 We do not relay non-local mail, sorry. in C:\xampp\htdocs\FinalTest\basket.php on line 75
Mail Sent.

what does this mean how do i fix it.

i'm using XAMPP on a windows XP machine

this is my code so far

<div id="detailsform">

<?php

$to = "[email protected]";
$subject = "Test mail";
$message = "Hello! This is a simple email message.";
$from = "[email protected]";
$headers = "From: $from";
mail($to,$subject,$message,$headers);
echo "Mail Sent.";

?>


<form name="personaldetails" method="post" action="#" onSubmit="return ValidateForm()">

<p>Forename:<INPUT type='text' name='forename' size=20 maxlength=20></p>
<p>Surname:<INPUT type='text' name='surname' size=20 maxlength=20></p>
<p>Address Line 1:<INPUT type='text' name='address1' size=20 maxlength=100></p>
<p>Address Line 2:<INPUT type='text' name='address2' size=20 maxlength=30></p>
<p>Address Line 3:<INPUT type='text' name='address3' size=20 maxlength=30></p>
<p>Post Code:<INPUT type='text' name='postcode' size=8 maxlength=8></p>
<p>E-Mail Address:<INPUT type='text' name='email' size=20 maxlength=100></p>
<p>cardtype:<select>
<option>mastercard</option>
<option>visa</option>
<option>maestro</option>
<option>solo</option>
</select></p>
<p>Bank Account Number:<INPUT type='text' name='banknumber' size=15 maxlength=15></p>
<p>Issue Number:<INPUT type='text' name='issue' size=2 maxlength=2></p>
<p>Expiry Date:<INPUT type='text' name='expirydatemonth' size=2 maxlength=2>/<INPUT type='text' name='expirydateyear' size=2 maxlength=2></p>
<p>security code (last 3 digits on back of card):<INPUT type='password' name='issue' size=3 maxlength=3></p>
<input type="submit" name="Submit" value="Submit">
</form>
</div>
</div>