Auto Delete users in group after 45 days

[hurrican]

I am looking to delete my users who sit in the "Awaiting E-Mail Confirmation" Group for more than 30-45 days. I found a cron job that will delete inactive users, but i'm not quite smart enough to figure out how to make it delete users only in a certain usergroup if in that group for 45 days.. Would this be the script that I'd need to run?? Any help would be GREATLY Appreciated by you SQL gurus

PHP Code:

<? 
//Delete non-activated members after 45 days 

require ("./global.php"); 

$DB_site->query ("DELETE FROM user WHERE  joindate > '".(time() - 3888000)."' AND usergroup=2"); 

?>