Replacing ethernet card on Sony Vaio VGN-FE670G?

I have a sony vaio FE-670G that I use as my mobile computer, my main laptop is a large sager and a desktop replacement. Anyways, the ethernet card has been burnt out for a long time now and I need to replace it. I am 100% positive it is not a driver error etc, the card is fried. I am having trouble determining whether or not I can replace the ethernet card alone so I was hoping someone here could help me make that determination. One theory I have is that it might be part of the motherboard and not a separate component.
Can someone please help me determine whether or not I can purchase this replacement part by itself and guide me to where I might find it?
If I cannot purchase the ethernet card by itself are there any other options I have to get a permanent ethernet input for this laptop?

Besides the obvious convenience of having a working ethernet port, the main reason I need it is I have a custom, hardened version of Gentoo that I have created but cannot get the internet working via the wireless card when running this OS off the hard drive. For some reason the wireless does work when I use the liveCD but not when I run the OS off the machine. Many people have tried to help me with this, including the guys that taught the class I took to learn how to create the hardened gentoo. It's just a fluke and there is no fix.


My wireless card works but has issues, for instance the little light above the wifi on/off switch goes on and off a lot and I have to get the switch in a certain position for it to stay on. So besides needing ethernet for the gentoo OS, I don't want to deal with this wifi when I am at home. I am not sure if the issue here is with the wifi card itself or something else that has to do with the on/off switch and/or the motherboard. If anyone is familiar with this issue I could use some input on what I need to replace to fix this as well.