Connection Problem

We have a notebook computer with Windows 7. It connects to our wireless router, but will not continue on to the Internet. I suppose it's something simple, as usual, but I am unable to put a finger on it. Anyone had the same or similar problem?

I'm assuming the router is already configured for Internet access.
Did you use the Win 7 network connection setup utility for the laptop?

Yes, the router is configured and works with several other computers. Something happened to this computer, as it used to work fine. I will check the set up again, but I'm pretty sure it was set up using Windows 7 connection set up.

The windows troubleshooter could not identify the problem.
The computer that I am on, as I type, is XP and I can't compare the settings on the Win 7 unit to see where the difference is. I know it's some stupid little thing, but I'm lost.
Thanks for any help you can give me.