To install the carl9170 firmware you need to determine if you are running a 64 or 32 bit version of Ubuntu.
Applications -> Accessories -> Terminal
Run "uname -a" in the terminal and look for 386 and 686. If you see either of these you are running 32 bit version. Otherwise you have a 64 bit version.
Onto the installation:
1. Install the following packages on 32 bit versions of Ubuntu (in this order):
Install the following packages on 64 bit versions of Ubuntu (in this order):
2. Hold down the ALT key and press F2 simultaneously to run xterm (or open a terminal window from Accessories -> Terminal).
3. A Run Application box will appear where you need to enter "gksu gedit /etc/modprobe.d/blacklist.conf" without the quotes.
4. Enter "blacklist ar9170usb" without the quotes at the bottom of the file and save.
You should now be able to select an access point using the network applet. In 10.04 and 10.10 the network applet is found at the top right.