I just got broadband, finally, because I live in the bloody countryside in Missouri.

To start, when I connect directly by Ethernet cable to my iMac I get the IP address 24.xxx.xxx.xxx The internet works just right.

Because I have two computers, the other a Linux/Windows box. I would like to use the wireless router to give both computers high speed internet.

The problem is that when I hook my gateway directly into my Airport Extreme, my iMac still receives the 24.xxx.xxx.xxx address. I get wireless internet just fine on my iMac but my PC box get nothing. In fact while my iMac get the 24.xxx.xxx.xxx address, my Airport get a address of 10.0.1.1 and my PC get address 10.0.1.2. It seems that the airport is giving itself a client address and iMac the ISP-given address.

Shouldn't my Airport get the 24.xxx.xxx.xxx and the clients recieve the 10.0.1.1 series addresses? I don't know much about this stuff.

Here are the settings of my Airport and all client computers
Airport
Connect using Ethernet
Configure using DHCP
Distribute IP
Share single IP using DHCP & NAT
Using 10.0.1.1 Addresses
Airport IP: 10.0.1.1 <-- does this conflict with iMac router info below?
On the DHCP Client list it has no clients listed.

iMac
Configure IPv4
using DHCP
IP: 24.xxx.xxx.xxx
Mask: 255.255.240.0
Router: 24.xxx.xxx.xxx <-- should this not be the router's IP and actually be 10.0.1.1 like the PC has it?

PC
Configure IP DHCP
IP: 10.0.1.2
Mask: 255.255.255.0
Gateway: 10.0.1.1