A quick translation for you....
ICS = Internet Connection Sharing, a built-in feature of Windows. It uses the computer connected to broadband (the ICS Host) to provide connectivity to another PC (the ICS guest) directly connected to it. It only works when both machines are on.
'Ethernet' is the type of cable that is currently being used to connect your modem to your PC. This connection method is generally preferred for reliability and speed (100Mbps). Chances are that you are using your only Ethernet port for the cable modem (broadband).
You probably won't be be using HPNA (Home Phoneline Networking) or ISDN (128k dialup) to connect your machines.
There are a few different connection types depending on what you have available...
I tried to keep some of the language simple, let me know if I left some in geek-speak. When I refer to a 'router', I mean a device which can intelligently direct traffic between connected devices. (Simplest definition I have)
* Wireless (a.k.a. 802.11a/b/g, wifi)
If one or more of your computers is a laptop with wifi built-in, this is probably the BEST method. It will allow you to use the internet just about anywhere in your home. This method requires some patience to set up. What you need is a
wireless router, which runs about $50. If you have a desktop you wish to connect, you can connect it to the router via
Ethernet cable (cheapest^^) or
wireless adapter (no wires!).
* Wired Ethernet, using the modem as a router
Your existing modem may be capable of acting as a standalone router. Just hook the cable modem to a
ethernet hub or switch. (Think of it like an intelligent splitter) Then buy two
ethernet patch cables^^ and use them to connect to your two computers. No configuration should be needed.
* Wired Ethernet via ICS
For about $40 you can get a
USB-Ethernet adapter that connects to an available USB port. (Saves you from cracking open the case) Then connect a
ethernet crossover able between the two computers and run the Network Setup Wizard.
* Wired Ethernet via a router
For about $50 you can get an
ethernet router. This will give a wired network capable of future expansion. (the ICS ethernet method only supports 2 PCs) It'll take a little work to configure, but once its set up, its rock-solid. Most routers also act as a good hardware firewall. This is the method I usually use to network desktops.
* Firewire
If by chance both machines have firewire (IEEE 1394), just buy a firewire cable and connect the two PCs. You'll be able to shuttle files around at a speedy 400Mbps (about 80x the speed of your broadband connection), and share internet access via the Network Setup Wizard (ICS). This isn't a traditional means of networking, but it can work. This option is only if you already have firewire, otherwise, use an Ethernet or Wireless method.
* Call the Cable company!
This is probably the easiest way to get hooked up. Chances are your broadband provider offers some sort of network setup service. They will charge you extra for equipment and labor, but you won't have to life a finger to have a working network. (I know Bellsouth likes setting up HomePNA (12mbps), not sure what cable companies use)
^^ Note: Stores like Best Buy/Circuit City severely overcharge for cabling. The other day I found some ethernet cable at a Dollar Tree, for $1. In most cases, gold plating = snake oil, don't let the salesman sell you a $25 cable. (Radioshack usually has reasonably-priced cable and competent staff to match)
Hope this was helpful, and not too confusing!