Problems connecting using Airport Extreme

I have a iMac, MacBook and PowerBook G4. They were always able to connect wirelessly until today using my Airport Extreme.
I reset the router. I shut off my Comcast router and then turned on the AE.
It gets connected to the wireless connection and gives me an IP address of 10.0.1.x. Signal strength is excellent but I can't get any web pages to come up. I connect an Ethernet cable from the Comcast router to my iMac and I get online w/o any problems.
The same result happens on the MacBook and PB G4.

When I put in the router address when connected wirelessly I cannot access the router.

I've never setup a Airport Extreme before. Any hints on this is done would also be appreciated.

What can I do so I get my wireless connection working properly again?

Thanks MacLovin78. After running the setup assistant I was able to get the wireless to work properly.
Next question is I have another airport extreme that is connected to a Dr. Bott extender in my living room. Then I have an Airport Express Base Station that is plugged into an outlet 15ft from the Airport Extreme in the living room. I need this to stretch the signal to my lower level.

I hooked up the Airport Extreme as a remote using the Airport Admin Utility. That works great.

Should I add the Airport Express Base Station as a remote also? If so, do I add it in the Airport Admin Utility the same exact way I added the Airport Extreme? If not, what is the best way to add the AEBS?

Thank you for looking.