It seems that I was drawing several jokers:
Toshiba Laptop Satellite 4100XCDT with ToPIC97 chipset and
DFE-650 Fast Ethernet PCMCIA card
The kernel I installed is 2.2.13 PCMCIA package 3.1.3-2
3Com 33589D and Xircom CEM56 work, so I asume there are no errors setting up the software. All seems to be ok. I read that there are problems with newer DFE-650 cards, but not if they are fixed or not. Does it make sense to upgrade at that stage or buy another card?