Maybe this should be a FAQ? :-)
http://slug.org.au/lists/archives/slug/2000/October/msg00359.html and http://slug.org.au/lists/archives/slug/2000/October/msg00388.html
In a nutshell, grab new drivers from www.scyld.com. Last I checked, they were only available as RPMs or tarballs, so you'll need to compile them from source.
Once they're going, I've found them to be pretty good cards. I'm leaning towards them a little more since finding out that the tulip driver for my Netgear FA310tx doesn't do the cool zero-copy stuff.
Cheers,
Peter