rare configuration with 5 NICs, problem for your brains

Hi!
Well its hard, and any modification are welcome, but there are lots of restrictions.-

Here at my work i have internet access behind a netscreen ( ) well, as the administrator have control list based on Mac Addres, i use only one PC to connect internet, this pc, have three NIC adapters, one to connect to the netscreen and have internet on that pc and two more to connect to two other coputers, so i created a bridge between this two nics, and have my connection to the netscreen shared, so I have internet on three pcs

Well thats ok, now here is my problem; In one of the two pcs i have a intranet connection too (two NICs), and If I want to have internet i have to disable intranet,

What do i have to do to have the two connections up, and route the internet traffic to the nic that have this info?

All pcs have windows XP, bridge connections and shared have automatic settings set by xp defaults

Lan have DHCP enable, but maybe i can do something if you need it to be static

Thank you very much in advance

Just watch out. If the software detects a new mac address that it has no info on it can block all traffic to that mac address. Send a message to your WAN guy and he will come looking for you.