Better yet...Try downloading this script. It is a stripped down version of the script that Chris posted above using the TranslateName UDF. That way it will work for any user no matter their AD directory.

ldap_dept.kix

The only thing you have to change in the script is the server to map the drive to...It is currently \\server\ and you will need to change this to your server name. Besides that there should be no needed changes. See if it works.