On the Ubuntu computer create a folder on the desktop called network-drivers
on another PC download this file:http://launchpadlibrarian.net/111339115/linux-backports-modules-cw-3.4-3.2.0-29-generic-pae_3.2.0-29.14_i386.deb
and copy it do the network-drivers
folder you created on the Ubuntu desktop
Now open a terminal and run:
Or just double-click the file to install.
If networking doesn't automatically start working, run:
Once you've done that and you have a working internet connection, it would be a good idea to also run:
sudo apt-get install linux-backports-modules-cw-3.4-generic-pae
running any updates .. as without that package, a kernel update will break your network again (requiring a different driver).
Once you have both of those installed .. feel free to delete the stuff from your desktop.