More for my reference, as I keep forgetting the files – these are the files you need to edit when connecting to a network – which I have had to do lately when driving the car around work.
In the interfaces file, I have set a static IP of 192.168.0.24
iface lo inet loopback
iface eth0 inet dhcp
iface wlan0 inet manual
iface wlan0 inet static
In the wpa_supplicant.conf file, multiple networks settings can be specified, I added my work network in here too, but had to use the field ‘scan_ssid=1′ to indicate it was a hidden network, and put the network name and key in as normal. When you fill in the form to connect to a network in the WiFi Config application, it adds an entry here with your entered data – so a good place to look if you mistyped a value. After returning home, I found that my home network had ‘disabled=1′, and it wouldn’t automatically connect. Without that line, it connects automatically.
group=TKIP WEP104 WEP40