Hi,

We must create a login mapping between the linked servers. When SQL Server connects to a linked server in order to execute a distributed query or a stored procedure, it looks for any login mappings for the current login that is executing the query of the procedure. If there is one, it sends the corresponding remote login and password while connecting to the linked server.

Security for Linked Servers: http://technet.microsoft.com/en-us/library/ms175537(v=sql.105).aspx

sp_addlinkedsrvlogin: http://technet.microsoft.com/en-us/library/ms189811.aspx