Need help making router find internet

[Sam1911]

Hi, all. Sam's wife writing; you were so helpful when we had major virus issues a few months ago, so I thought I'd see if someone can help with this issue.

We have a DSL cable modem for our internet connection. It works fine. We also have a Netgear router; we've not been using it recently, but it worked fine a few months ago. Now we want to network a second computer to our main one, using the router.

I've connected the router, and I think I have everything plugged in to it correctly. (Power, of course. Ethernet cord from modem to the "internet" spot on the router, then another ethernet cord from the "computer" spot on the router into the back of the computer. Right?)

Nothing happens. All lights (4) on the modem are on; all applicable lights on the router are on (also 4). But the internet won't work, on the main machine, to say nothing of the secondary one. Both say that they find a network, but it has limited or no connectivity, that it can't renew the IP address. We are running Avast and Comodo; I disabled those, as well as the Windows Firewall, and still nothing. I tried restarting the machine -- nothing. I tried doing the ipconfig/renew that I found suggested here -- nothing. I tried pushing the rest button on the router -- nothing.

I had it working very briefly two days ago, but then it suddenly quit and hasn't worked since then. I didn't change anything; it just didn't work.

Suggestions? This computer is running WinXP 5.1, service pack 3, if that helps at all. The router says Netgear Wireless Router WGR614 v3.

Thanks in advance!

-Sam's Wife