School Project Help

For this site we're making for a school project
i need to be able to make images that just who an email address
this to help prevent the spammers harvesting our emails...
whats the easiest way of doing this?

i'm thinking of doing like
<img src="image.php?user=$id">

and a case statement or something to that effect...

Any ideas?

Update: Never mind, i didn't have gd installed for php
Update 2: Still need help for basics...
I need to be able to use the MS Comic Sans font..
as the rest of the site is made using the font..
source:
<?php
//header('content-type: image/jpeg');
header('content-type: image/png');
$im = @ImageCreate (50, 100)
or die ("Cannot Initialize new GD image stream");
$background_color = ImageColorAllocate ($im, 255, 255, 255);
$text_color = ImageColorAllocate ($im, 233, 14, 91);
ImageString ($im, 1, 5, 5, "A Simple Text String", $text_color);
//ImageJpeg ($im, '',100);
ImagePng ($im)
?>