Just a question, but seeing as I'm probably building a Media Center anyway, I might as well ask. I am currently behind a combined Router/Modem, so I obviously couldn't get my planned hybrid between them (i know there are thin clients, but I don't think there's one that would fit INSIDE the box ) So I was wondering If it would still havre full functionality?
Yes you could...
You would connect your Core's WAN side NIC to your existing 'router/modem/ and have it issue a DHCP address to the Core's WAN side (or set a fixed address for the WAN side in the range that your 'router/modem' is setup for).
Now on your Core's LAN side NIC you attach a network switch and then attach all your LAN devices to this switch or other switches connected to it... ie MD's, IP Cams, Squeezeboxes, IP Phones etc etc etc.
There are are plenty of Forum threads on this... and Wiki pages too.
All the best
Andrew