To Modify User Info in a domain:

- Open command prompt in Admin mode and run the below command:

C:\Documents and Settings\Administrator\Desktop>ldifde -i -f exportOut.xls -s DOMAIN_NAME

-- exportOut.xls will have the user info details exported with some fields modified for the users.

Useful links:
http://support.microsoft.com/kb/555636
http://www.activewin.com/win2000/step_by_step/active_directory/bulksteps.shtml