Firewall Configuration?

I just purchased a soho3 and intend on intergrating it with my single 2000 server (No web or mail servers). Currently, one NIC is connected to the router for my WAN, and the other NIC is connected to my switch for my LAN. I am using the server as arouter to serve my clients since I’m only using one static IP.

My question?

Should I be placing my firewall between my server and my router? How should I configure the firewall? Everywhere I read the firewall is running from the router to the switch, not the server. But since my server is acting as a router, this can’t be the case….. I’m lost to as how I should assign static WAN IPs…

Any suggestions would be great!

Thanks in advance….
Chaz