Backing Up Active Directory

I have been asked to install a "replacement" terminal server by a company who's existing terminal server is experiencing what appears to be hardware related issues.

What I'm trying to work out is the best way to transfer the information from the existing server to the new one. Does anyone have any recommendations for applications best suited to this task?

The OS is Server 2003 Standard.

The client mentioned running the new server as a file server for the time being but backing up the active directory so that if the Terminal Server failed completely we could add the role of terminal server to the new server and restore the active directory there, personally I think this would a, be a mistake to rely on hardware known to have issues and b, probably not work in reality the way they see it in their mind.