The way I would "key" a wireless network is to use the Wireless Network Setup
Wizard, even if your AP doesn't support Windows Connect Now functionality.
First, work through the Wizard.

In the first screen, select "Automatically assign a network key" and
determine your SSID yourself. Here, the PC determines the WEP or WPA key
randomly.

In the second screen, select "Set up a network manually".

In the last screen, select "Print network settings". You will see a Notepad
screen with the network settings as a "rap sheet". Save the "rap sheet" to a
UFD and print it out.

Log in to your AP and set the SSID and WPA key according to what you see in
the "rap sheet" and confirm these settings

Restart the Wireless Network Setup Wizard and select "I want to add devices
to the network" option.

Select the "Use a USB Flash Drive" in the second screen and follow the
instructions here on to set up your wireless-capable laptops to the network.

If you are lucky enough to have a router or AP with Windows Connect Now,
work straight through the Wizard once, but set the AP first when "dipping"
the USB flash drive in to the devices.

Whever you change the network key, use the Wireless Network Setup Wizard for
this purpose. I always have said this that it works in a similar manner to
any door lock that works with a key. With these devices, the manufacturer or
the locksmith who rekeys them doesn't need you to determine what the key
"cut" will be. You are also sure that your neighbour's front door key will
not work your front door lock and your front door key will not operate your
neighbour's front door lock, even though both locks are from the same
manufacturer and use the same keyway.

This program uses the maximum key-length possible, which is equivalent to
using a lock that works on 5 or more pins or levers compared to using one
that uses 3 or 4 pins or levers like some cheaper padlocks. Here, the more
pins or levers yields more "changes" (many different keys) and less risk of
other keys opening your door.

With regards,

Simon Mackay