I assume alot here, but correct me if I'm wrong.
During boot get into the bios area and verify the ethernet port is active or enabled, if so exit out, if not then check it or do what's required to enable.
Now, upon booting into the system, if the new h/w message appears(have your orginal system/mtrbd. CD) follow prompts. Just point to the dir. on the CD if possible by manually "browsing" to the driver section. Otherwsie, exit out and cancel the driver install. Under the same CD, run it and find whatever section allows to install the drivers, it maybe more than one or the ethernet by itself. Once done, reboot and check results. If you don't have the orginal mtrbd. CD then via thier support website for your mtrbd. or system model# proceed there. Verify, that you are getting the *right driver* for your ethernet port, otherwise, it will get confused or not install properly. If none of this seems to work, you may have a bad h/w or truly corrupted pgm/driver(improper). To get away from all this, buy another ethernet card($10-20) 10/100mb models and install, make sure to uninstall the old ethernet port and/or disable, before you install new one.