Q:

What "flavour" or type of LAN should I be using?

I have Lubuntu 14.04 installed & running well on an old P4 machine (32 bit).
I have Ubuntu 14.04 installed and running well, as a dual boot with WinXP, on a newer Core2Duo Asus MB system. Ubuntu is 64 bit - the WinXP is 32 bit.
Each system is connected by Cat5 cable to the DSL router supplied by the Aliant (Bell) telephone company. (I have no information other than it is labelled "SpeedStream" and provides us with very slow "High Speed" 200Mb/s max). Both systems connect automatically to the Internet and seem to operate well.
What I want to be able to do is transfer files between these two computers - nothing more. Can someone please tell me which type of LAN (eth0, DSL, IPv6, etc.,) I should configure? It would also be an enormous help if someone could tell me where and how to find ALL the necessary info to fill the boxes in Network Settings, etc.
BTW when I run ifconfig I get 3 "paragraphs" - eth0, lo, ppp0 - and all are UP and seem to report no conflicts or problems.

A:

eth0 = Ethernet 0 = Wired connection
ppp0 = Point-to-Point Protocol 0 = Connection to the Internet
lo0 = Loop-back 0 = doesn't connect to any other computer then your own.

Warning: All the below links are provided for documentation purposes only (a.k.a. RTFM).  Don't install anything from these sites, just use the Ubuntu Software center!

If you don't know anything about networking, the easiest to install would be the Very Secure File Transfer Protocol Daemon (Daemon = "server")  For obvious reasons, you'd bind it to eth0 so it doesn't have to go all the way to the Internet to exchange files and you'd have to install it on both machines, turning them both into servers and would access the files from one of the clients to one of the servers with something like FileZilla 
The easiest to run would be Samba which turns your PCs into Windows-like servers, allowing you to use the file manager and to just browse files on the other machine (again: if you want both machines to be servers: install it on both.)
However Samba would be a tiny bit more difficult to install.

If I were you, I would start off with 1. and if you get fed up with having to go to FileZilla to exchange files, go on to 2. (or don't if you're happy with it)

