Hi all,
First off, I too was a frustrated player that, due to the fact I had an AMD Nvidia (nforce4) mainboard, (DFI DAGF-4 to be specific) I was unable to connect or join any sort of networked game. The moment I tried it would CTD and give me an error stating that my kernel32.dll crashed out.
So, my roommate brought home a simple Linksys USB LAN dongle. It works just fine now. We installed the USB dongle, uninstalled the inherent Nvidia Network Access Manager, switched over to the new USB device and let 'er rip. So, now I keep both connections available, but when I want to play ArmA online I plug in the USB dongle, allow windows (XP Pro) to find it and play. When I am done I go back to my standard built-in LAN. Apparently, it will only crash when it accesses that specific Nvidia driver, and not if it is generally left on your computer.
I am now a happy camper, and I did not have to open my tower to install a PCI NIC. I just had to plug in a USB dongle.