Network configuration Red Hat Linux

Hi everybody
I have Red Hat Linux 9 and recently I added NIC to my computer, it recognized it fine and prompted me to configure networking during the boot.
After that whenever I enable NIC my dial-up connection dies but if i deactivate NIC(eth 0) and than dial-up again it works fine,
/etc/resolv.conf loks like this:
nameserver 192.189.54.26
nameserver 192.189.54.37

Does anyone have an idea of how to solve the problem,