I have high speed internet through my cable modem using an ethernet cable and a network card. I now want to network with another computer but, on the back of my modem, all I see is an available USB port. Does that mean that with my new computer I have to connect using USB or is it better to buy a new modem and stick with ethernet?
To provide internet connection to more than one computer and network them, you would probably be best served by purchasing a router. If you don't need wireless access, you can get a generic 4-port router pretty cheap. If you need wireless access, you might read through here to see what kind works best with Comcast (apparently some models are more compatible than others).
Thanks. I did buy a router today. I've familiarized myself now with how it all works and hooks up. I'm just not sure if I would benefit much from having one computer connected via USB and the other through ethernet. It seems those are my only options with my current cable modem, which is the Motorola SB4200. I'm thinking that I should buy a new modem that supports only ethernet for fastest speed? I suppose then I will have to call Comcast and reconfigure my setup. I'm not sure?
It sounds as though you're a little confused. The USB port on the modem is only for people who don't have an ethernet card in their computers.
The modem should connect through the ethernet port to the WAN or Internet port on the router. Connections to the individual computers are made from the numbered ports to the ethernet ports on each machine.
Setup is pretty fool proof these days-just follow the directions and you should be in business in a few minutes.
Your cable modem should be fine. You don't need to get Comcast to reconfigure anything. And you can't connect two computers to one cable modem without using a router. If you plugged one into the ethernet port, and the other into the USB port, only one of them would work - whichever one you plugged in first.
Turn off the power to the modem, turn off the router, turn off both PCs. Go heat up a cup of coffee (you need to let the modem sit for a few minutes). Now, turn on the cable modem, and wait for it to come up completely. Connect an ethernet cable from the modem to the WAN port on the router, and turn on the router. Wait for it to come up completely. Connect one PC to one of the LAN ports on the router (usually numbered 1-4), and boot it up. Then do the same for the second PC.
We know the first time setting up a home network can be daunting. Post back if you encounter any snags (and include what make & model router you have).
As EO says above, the power cycle process is always key! The cable modem (cm) "learns" what MAC address it is connected to, which in this case, you want to be your router's. You have to power off the cm for a few minutes so it will "forget" your pc, otherwise it won't recognize the router.
Powering up the router next will allow it to aquire network information from the Comcast servers (using DHCP), such as its IP address (which is the only IP address the rest of the world will see regardless of how many computers you have on your home network) and the IP addresses of the Comcast DNS servers. Your computers will ask the router for similar info, again using DHCP, when they start up. So it is always best that the "upstream" device be up and stable before powering on the downstream device connected to it.
OBTW, if the router you got also supports wireless, there are a couple of additional steps you should take. If you are only using wired connections right now and the wireless was for "future expansion" of your net, you should disable the wireless function until you need it. If you do need wireless now, read Baric's excellant sticky note at the top of this forum on how to secure your wireless router!