The subway won't be fast enough for a pleasant use of an usb ethernet adapter.
The first one you show does not seem compatible anyway. The second should be working with dm9601eth.device unit 0, as the class is loaded by Poseidon.
PCMCIA NIC or any PCI/ISA/zorro ethernet board if you have a zorro bus/Ateo bus/Mediator or GRex bus would be much better.
