I guess I dropped the ball on this one. Let me respond to your second post. If anyone else reads this please feel free to chime in.
So if I understand you correctly, you would like to have 1 pc wired through the router going to the internet, and one pc wireless only on the lan. You are going to turn off wireless on both the router and the pc when not in use.
There isn't really a whole lot to configure, as it sounds like you already have the first pc setup.
For the 2nd pc all you need to do is manually enter an IP address similar to your first pc. So if you open up a command prompt on your 1st pc and type ipconfig it will tell you what your current settings are.
The default is using a 192.168.1.X network, a /24 subnet (255.255.255.0) and 192.168.1.1 as the gateway.
So on the 2nd pc I would add an IP address like 192.168.1.101 and give it a subnet of 255.255.255.0 This means that my computer can see any other device that ends in 192.168.1.0 - 192.168.1.255 If I don't specify a gateway then my computer doesn't know how to leave the network, so it won't try to access the internet. Also, I wouldn't specify a DNS server as I don't need to resolve an domain names.
For the wireless you'll probably want to use WPA2-PSK (Or WPA-PSK) and mac filtering. to get the mac of your linux cards wireless adapter type ifconfig in a terminal window. If you check out our manual for the device Section 7 has plenty of good info about setting up wireless. Starting at 7.5 they have pictures of each screen and details about what the options do. http://us.zyxel.com/upload/download_...2008-03-18.pdf