Dynamics GP - Copy Live to Test, or Change Database Name

Overview

1. Create new company
2. Give appropriate users access to new company (Tools>Setup>System>User Access)
3. Set appropriate currency access to new company (Tools>Setup>System>Multicurrency Access)
4. Backup live company
5. Restore live company over new company
6. Run company name update script
7. Run changedbowner script
8. Remove user access to old company

Detailed steps outlined here

http://support.microsoft.com/kb/871973