Try live cd such as knoppix.
Most newer pci cards support plug and play. If ISA, EISA or other bus or even older PCI it may need the drivers and bios settings correct before the OS would "see" it. Still could be a conflict.
They do go bad. One of the most supported nic's on the planet is also the least expensive. Realtek supplies a very good chip to many of the least expensive nic's you can buy. I have one that cost $4 and almost ever OS supports it.
There are also USB based that are about the same price.
"Best Practices", Event viewer, host file, perfmon, antivirus, anti-spyware, Live CD's, backups, are in my top 10