well, it took me a while but i finally figured it out.
the problem lies with the nic (dlink dfe-520tx). i put my OPT1 interface on the intel 10/100 Pro nic and it worked flawlessly, while the WAN on the DFE-520TX failed.
i have yet to replace the dlink nic (in the process of getting another intel 10/100), but i dont foresee any problems.
as for the the dhcp issue, i disabled the wan on the wrt54gl router and connected the pfsense LAN interface to one of the wrt ports, making it behave as a bridge. now all my pcs get their ip from the pfsense box.
i still have some work to do: port forwarding, openvpn, i want to be able to address the machines by hostname instead of ip, etc.
i'm attaching a network diagram for future reference.