This problem seems to exist with other Tulip-based cards. What I've had to do 
is hard-code both ends to be half-duplex, you should see much better results. 
Auto-negotiation seems to always fail, and full-duplex never seems to work.

-pjl

> >    Running the cards in full-duplex gives very poor performance.
> >    Below are two tests ran with netperf. One is a direct connection
> >    with a cross-over (which gives full-duplex as above) and one
> >    is through a hub witch forces the PHYs into half-duplex.
> > 
> > That's the standard symptom when one end is running in full-duplex 
> > mode and the other is half-duplex. 
> 
> But even if I choose full-duplex on both ends I get the lousy performance.
> 
> / Jonas
>