Did you run "Home and small office network" wizard?
Did you disable ICS on non-ICS PC if not XP OS?
Did you set fixed IP (192.168.0.1 and 192.168.0.2 etc) for your two PCs?
Did you disable ICS on non-ICS PC if not XP OS?
Did you set fixed IP (192.168.0.1 and 192.168.0.2 etc) for your two PCs?