Ooh, big project. Running linux is a good book to get you started, but you'll have to bend it a little.
Here's what I did for my network:
After bumbling around i ran redhat-config-network to set the hostname, and the ip address (I don't think you need to do this if it is enabled to use DHCP).
Sharing internet access is something tricky. you'll be using your linux box. once again, crack open Running Linux. also look at tldp.org
you have to run redhat-config-samba or point your web browser at localhost:901. read up about samba, there are a couple of online books about it at samba.org
Pick up a good book. Don't worry, just do the background reading and it should be a piece of cake.
I suggest setting up samba first.
I should go fine. Setting up a network was the whole reason I installed X, otherwise you have to mess with random config files and hope...