How to configure switching between network interfaces?

[mstrickland16 at nc.rr.com]

How to configure switching between network interfaces?
I would like to determine how, or if, the following can be accomplished with FreeBSD. 
Configuration:
A BSD box setup with 1 GbE NIC and a 4 port 10/100 NIC
The GbE interface will have a static IP configured (192.168.10.x/24)
Planned Implementation:
  Along with possibly serving other data such as NFS or HTTP traffic, I would like the interfaces to work as a switch. The GbE interface is a fiber optic NIC which connects to the rest of the network 100 or so meters away. I plan to use the other 4 interfaces to attach hosts to my network. I would prefer all of my hosts to be on the same subnet if possible, otherwise I would just configure routing between the appropriate interfaces. My question then is: Can the interfaces be configured to function as a switch would, allowing the connected hosts to recieve DHCP and other traffic "routing" from the fiber optic interface via the FreeBSD box. I know that in a basic configuration, 2 interfaces on the same subnet are not a best practice and would required special routing information. I assume that somewhere this can be configured. A good shove in the right direction would be most appreciated.
Thanks,
Mike