computer says connected but can't access internet?

I recently moved, and my computers worked fine before the move. Now that I am settled and trying to set them up again, this is what is happening. I am attempting to connect to the internet using my cable internet connection. The cable lights up in the back of the computer as it should. The computer does show that it is connected, but it will not access the internet. It will sometimes display the message "little or no connectivity". I have checked everything I can possibly think of, and it seems to me that everything is set correctly. All the connection properties are correct, as is the firewall. I have another computer which is set up and works fine on the internet, so it is not the modem or router either. I also checked the cables on the computer that is working correctly, and they are fine. I am having the same problem on 2 seperate computers. I am running windows xp home on both. One is a dell, and the other is an emachine.

Firewall settings?

I guess you are using a router as you have muliple computer.

1. Can you ping the router from each faulty PC?

2. If not, then change the cat 5 between a faulty PC and the router.

Because you can have bad connectors on the cables, or the nic in both could have given up. Yes, I have had both happen on the same rig.

i had a similar prob with one pc with little activity i turned it off and unplugged the modem and router after powering back up the pc that didnt have good connectivity was working fine . before the fix it was showing no gateway address but the power down fixed it.