It should work OOTB. If not, you could try to find NT 4.0 driver for your NIC and try to install it in ROS. No assurance for it to work that way though. If you try and dont find it working, you could get a second PC, connect both of their serial ports with Null modem cable and get us debug output with that NIC driver failing. This could help us to make that driver working. Still no guarantiees though...