Gigabit ethernet should work fine on regular cat5. But a regular crossover cable won't work with gigabit ethernet, due to gigabit ethernet using a different pin-out, and using all 8 wires. Most ...
Before you run that flat cable, make sure it actually belongs there.
Works fine for me. Just tick the ICS box on the computer with the modem. Set the other machine to a private IP, such as 192.168.0.2 for example.