External links through php file target=_blank + nofollow

I have my external links on my site in a php file which works like this:

The link on my site is e.g. /links.php?id=google

and it links to a file called links.php with my links in it. "google" is the id and it follows it to the link and goes to the site.

<?php
$path = array(
'google' => 'http://www.google.com',
'yahoo'=> 'http://www.yahoo.com');
if (array_key_exists($_GET['id'], $path)) header('Location: ' . $path[$_GET['id']]);
?>

Code (markup):

I need someone to help me put some html into the php code that:

1) makes the link open in a new window - target=_blank
2) makes the link nofollow.

The html has to be in the links.php file rather than the link, so either after 'google' => 'http://www.google.com', or in the if statment.

I have an idea that the nofollow can be put in metatags, but I am not confident it will work and have no way to test it. I need some guidance.

thanks.