I fine Linux Router project is a little hard to setup for newbies... so I suggest go with FreeSCO or Coyote Linux (see my above post for links)... Both site has a list of NICs that they work with... if your NIC is not on there, but u have the proper linux driver for it, then it's no problem...
Just download their program and create the floppy... depending on which one you use, you either configure it before or after you create the floppy... there's absolutely no coding required, same as setting up any program... It runs you through step-by-step and ask you for the information (like external IP address for your cable modem, internal IP for your LAN, DNS, etc... )
Once you configured the program and created the floppy, it's good to go! Just set the gateway of all your other PCs on your network to the IP of the linux box, and they will access the internet through it...
Then, all you need to do is boot off the linux floppy (write-protect the floppy too, so you don't accidently erase it) you created... There's really no need for a monitor, mouse, or keyboard also, cuz you don't really have to type anything it, and almost never crash...
I think they recommend 16 MB ram, cuz these linux routers work by creating a RAM drive instead of using the harddrive... if you dont have that much ram, you will need to leave your harddrive in there for it to use... otherwise take your harddrive out if you want, it won't ever use it...
You are welcome to e-mail me or post more msgs on this board if you need more help... play around with it for a while, it should not be hard to get it working... the hardest part for me was getting the NICs working properly, cuz I had one of those cheap ones @Home gave me...