I no longer have the manual to the modem/router! But, I will buy a new modem and a new router anyway. This one came from my ISP, so it may not be very good.
I have my spare WRT54GL set up with DD-WRT, and it acts as my DHCP server. I have some of my routing still on my modem because I haven't gotten around to putting it in bridge mode. Everything is plugged into this router, and I have a Wireless N access point (not compatible with DD-WRT) for faster NAS -> laptop transfers.
I bought a domain name, set it up with freedns.afraid.org, and made the appropriate port forwarding rules so I can access my server from the outside (work, parent's house, etc). I plan on setting up my FreeBSD NAS as a DNS server so it can resolve my domain from within my home network, and then set up our laptops to mount the NAS as a network share off the DNS name, so I can access my files anywhere.
I highly recommend this setup. Hopefully this helps give you some ideas!