The Farallon card sounds like it's operational. If you wanted to try something else, I maintain an EtherLink III driver here ( http://www.floodgap.com/retrotech/mac/enet3c589/ ), but I actually suspect the problem is on the router side. Does your router work fine with other 10Mbps devices? Have you tried giving it a static IP from the DHCP range and seeing if it can get out? AppleTalk does not need to be active for this.

The 1400 is a fine notebook, one of the best keyboards on any laptop, and very hackable. I love mine to this day.