Some more information would help.
What distribution are you using at this time?
What is the output of 'lspcmcia'?
What is the output of 'ifconfig -a'?
My first thought is that the onboard network is being recognised and being assigned to eth0. The PCMCIA card may be being recognised as eth1. Maybe you can turn off the onboard network in the BIOS.
This is an old document that may be of use.