Download the 3Com-driver from Aminet. The cnet-driver will not work with a 3Com card.
You also have to find a suitable tcp/ip stack, otherwise there's nothing you can do with the card. OS 3.9 comes with such a stack (Genesis), but OS 3.1 doesn't have it as standard. I seem to remember there's a demoversion of AmiTCP on Aminet, but I'm not sure of that.
My 1200 with 68060/50 works very nice with OS 3.9 and a 3Com589. Surfing the web sucks (no RTG, just AGA), but other stuff like FTP, e-mail, chatting and usenet do work like a charm.
