I have the same problem on a Dell Precision 390. I have two ethernet cards, one broadcom integrated on the motherboard and an other broadcom separated. The card that isn't integrated with the motherboard works good after the installation of RHEL 4 (without any additional driver). But the integrated doesn't work, so we built and installed the latest tg3 broadcom driver with the same procedure quoted in this post (rpmbuild -bb work well for us
). But unfortunatly, the ethernet card still unrecognized and it doesn't fix the problem.