you're right about the ne2000 and the file server.
the file server device set is a fairly small subset
of the cpu/terminal support, based on what has been
used to build file servers.  since
those are typically built to give some degree of
performance, ne2000/8390-based things might not
be the cards of choice.  one way or another that
device support will improve, but that doesn't do you
a lot of good now.

in ether82557.c make sure it reads
		if(bmcr & 0x2000)
			ether->mbps = 100;
		else
			ether->mbps = 10;
and specifically that the else isn't missing.