About Exchange

Hi,
I have two exchange question.
1) I have two sites in exchange but I have noticed if i changed anything on one site then changes not replicate to other site.Replication time is 1 hour but still it not replicate.
2) I have windows 2000 enterprise server and installing Exchange 2003 but not sure about exchange 2003 install on forest or domain level.
I would appreciate if someone assist me on this.
Thanks and Regards.
Anurag.