Exchange 2000 FE/ BE configuration

I’m trying to configure a W2K Exchange Server frontend/backend configuration with a DMZ. I have a Watchguard SOHO firewall and also a Smoothwall firewall to work with. I have succesfully logged on with OWA client through the Frontend without any firewalls so I believe that its all in the firewall configuration now. The T1 router maps a public IP to the external side of the SOHO “192.168.2.X”. The SOHO then creates the NAT to the internal network IP scheme “192.168.1.x”.
The question is how to config the F/E behind the SOHO in a DMZ and the B/E behind the smoothwall.
Authentication,DNS,IP Schemes,and Microsoft have me buggin!!!!

Has anyone done this or a similar config.?

Thanks.