Hi -
You can do this from your Unity server's Active Directory Users and Computers console. On the Unity server, go to Start - Programs - Exchange - Active Directory Users and Computers. On the left side of the console, click on your domain. Use the search button on the tool bar to look for the user. When you find the user, double-clink on the user to open up the user account properties. Correct the spelling of the user's First name. Through replication, the change will appear in the Unity SA and get populated to the UnityDb.
Ginger