Fully Connected to AirPort Extreme, But With No Internet (PLEASE HELP!)

Question

I have spent my Labor Day trying to figure out what is wrong with my wireless connection to no avail. I am entirely frustrated and would appreciate any helpful advice that can be offered.
Here's the deal:
Yesterday afternoon, the two computers on my wireless network (an iMac PowerPC G4 and a Dell Inspiron E1705 laptop) lost connection to the Internet. We had lost power earlier in the day, but didn't have any issues immediately after it was restored. A few hours later, it just stopped.
Today, I started troubleshooting to figure out how to fix it. The Dell had no trouble finding the network and connecting, but it was only connecting "locally." Same with mine. We've also got a Nintendo Wii connected wirelessly, but it was also not working. Lastly, we have an HP Photosmart C4280 printer plugged into the AirPort's USB. Despite not being able to get on the Internet or restore Wi-Fi to the Wii, we are still able to print without issue (from both computers).
At one point, I got Internet back on my iMac, but I kept messing around with the network settings in the hopes of getting everything back to normal and lost it again. I've been mainly playing around three different settings: the AirPort Admin Utility (changing Channels in the AirPort tab, checking boxes in the Network tab, etc.), the AirPort Setup Assistant (messing around with the Wireless Security), and the Network Control Panel (clicking things I don't understand in the TCP/IP tab, etc.).
At first, I thought the issue was with my security settings, so I tried setting up the AirPort without a password, and still could not connect with the iMac, Dell, or Wii. In a last-ditch effort, I went out and bought a Linksys Simultaneous Dual-N Band Wireless Router, which restored the Internet to the iMac, Dell, and Wii. Problem is, I love the AirPort (and do not want to sacrifice wirelessly printing through its USB).
I am completely frustrated! If anyone has any suggestions whatsoever, please help me out. It would be greatly appreciated!!
Have a great night!
TK

Answer 1

Ok, I'm going to assume that you are using the newer AirPort Utility and not the older AirPort Admin Utility that originally came on the CD with your AEBS.
If this is correct, the following would be the basic settings:
Either connect to the AEBS's wireless network or temporarily connect your computer directly (using an Ethernet cable) to the LAN port of the AEBS, and then, using the AirPort Utility in Manual Setup, check these settings:
AirPort - Base Station tab
o Base Station Name: <whatever you wish or use the default>
o Base Station Password: <enter the desired administrator's password, the default is "public">
o Verify Password: <re-enter the desired password>
o Set time automatically: (optional)
o Allow configuration over Ethernet WAN port: (optional)
AirPort - Base Station - Base Station Options
o Contact: (optional)
o Location: (optional)
AirPort - Wireless tab
o Wireless Mode: Create a wireless network
o AirPort Network Name: <whatever you wish or use the default>
o Radio Mode: 802.11b/g compatible
o Channel: Automatic
o Wireless Security: None
AirPort - Wireless - Wireless Options
o Multicast Rate: 2 Mbps
o Transmit Power: 100%
o Create a closed network (unchecked)
o Use Interference Robustness: Not enabled
Internet - Internet Connection tab
o Connect Using: Ethernet
o Configure: Using DHCP
o DNS Server(s): (optional)
o Domain Name: (optional)
o DHCP Client ID: (optional)
o Ethernet WAN Port: Automatic (Default)
o Connection Sharing: Share a public IP address
Internet - DHCP tab
o DHCP Range: <leave default or enter desired range>
o DHCP Beginning Address: <leave default or enter desired beginning address>
o DHCP Ending Address: <leave default or enter desired ending address>
o DHCP Lease: <leave default or enter desired lease duration>
o DHCP Message: (optional)
o LDAP Server: (optional)
Internet - NAT tab
o Enable default host at: (unchecked)
o Enable NAT Port Mapping Protocol: (unchecked)
Once you verified that you can get Internet access for all of your computers, you should secure your wireless network. To do so, I suggest that you make these changes:
AirPort - Wireless tab
o Wireless Security: WPA/WPA2 Personal or WPA2 Personal
o Wireless Password: <enter desired wireless encryption password>
o Verify Password: <re-enter desired wireless encryption password>