In Ubuntu 8.04 the Intel wireless cards have switched from the ipw driver to the iwl driver. The version of the iwl driver that ships with Hardy is slightly buggered. The driver does not support SCAN_CAPA = 0×0 which prevents it from connecting to hidden networks. Though Network Manager has been pachted with a workaround for this. It also doesn’t have any support for controlling the LED light. Luckily a new version of the iwl driver has been backported in the linux-backports-modules-hardy-generic package.
To install this package, first go System→Administration→Software Sources. Go to the Updates tab and enable the Hardy Backports repository.
Click Close then click the Reload button when prompted. After that is done open a termianl and enter
sudo apt-get install linux-backports-modules-hardy-generic
Afterwards, reboot and you should have your LED light working as well as possibly better wireless performance.
I still have some problems connecting to my network. Sometimes it won’t connect when I boot the computer and I have to fool around with Network Manager by disabling wireless, enabling wireless, disabling networking, enabling networking, and a number of combinations of those things with some waiting thrown in there too. So if you’re having problems connecting to the network, play around with Network Manager for a while. It might take a lot of tries.
Copied as is from linuxtechie.wordpress link