one site exchange server

Hi
our organization has one PDC and one exchange 2003 servers. and recently we have statrted a new office apporx 10 Km from our main office which will be having a 2MB lease line connection between the two offices. our company wants to have another child domain and a another exchange server in the new location in order to avoid load in the main office server. i have config. setps for the child domain but i dont have any idea how to configure the exchange in the branch office which will reterive mails from the head office server in order to server the clients citting in the branch office with avoind load on the main exchange server.
please let me know if you any info.