1. Is there any command in SQL Server that can tell me which remote login on the linked server have I mapped my local login
2. If I use below command to map a local user: Locallogin to the domain administrator
sp_addlinkedsrvlogin 'mainsql', 'false', 'Locallogin', 'Administrator', 'pwd'
What will happen if the domain administrator's password may change in the future Should I execute sp_addlinkedsrvlogin with new rmtpassword again

Questions about sp_addlinkedsrvlogin
bruce_heath
If this is SQL SERVER 2005 you can use the catalog view sys.linked_logins. This when joined with catalog view sys.servers should give you the information you need.
I am not very sure about the second question ; hopefully someone else can give you a better reply. Have you looked at books online for this
akortz
Unfortunatly, I use SQL Server 2000. It seems that SQL Server 2000 does not have catalog view. :-(
After all, thank you for your informational reply.