Description of problem: Remove 3c590 from one slot, insert realtek 8169 in another. Tell kudzu to remove one configuration and use the other. Kudzu generates eth1 not eth0 lines and it doesnt work. Remove all the config, redo the card as eth0 and it works
Using eth1 could be expected. Not working isn't. What's the /etc/sysconfig/network-scripts/ifcfg-* and /etc/modules.conf after the bad change?
Please try the kudzu-1.1.36.1-1 packages at: http://people.redhat.com/notting/kudzu/ These may resolve some of your issues.
Please try the test RPMS at: http://people.redhat.com/notting/kudzu/
Should be fixed in the last FC1 update.