> My thinking is, that in a peer-to-peer system, the original computer will use
> "LOCALHOST" as the server, and the new, additional computer will use the host
> computer name (rather than the IP Address).

Good!

> I have already created a Data Path Configuration utility that uses a directory
> tree for the user to "find" the .FDB file via the network. Once that file is
> found, the utility records the host name and data path in the Windows Registry
> so the main application can act accordingly.

The more common way to do this, would be to add an entry in the aliases.conf file on the server pointing to the database. Then, the new additional computer would only have to know the host computer name and the alias you've defined yourself. No need for the additional computer to know the physical address of the database, it doesn't even need to be able to see the directory (it is the Firebird user on the server that accesses the file, the logged on client only communicates with Firebird).

HTH,
Set