One of the first things you should do in this case is check to see if your Ethernet adapter is supported by the Linux Kernel.
The following link will tell you just that.
http://www.tldp.org/HOWTO/Ethernet-HOWTO.html
Anyways, this is the first step...try that and see what you come up with.
Ben
PS. You should really look around on
www.tldp.org and invest time in reading various HOWTO's listed there. Many people spent many many hours writing them, for you and all other linux users to use for free.