Help! Exchange server 2000 domain.

Hi, I'm new to Exchange server 2000 but now I have to install it for our company. The problem is about the domain: My local win2k Domain is abc.local and the Internet domain name what I own is abcusa.org. Does it possible to install Exchange server into my domain server which is hosting abc.local and let my email address to be @abcusa.org (how to implement it)? Or I have to install another Win2k server for domain abcusa.org? Any idea will be appreciated. Thanks!