I assume it means ndisgtk; I can't find anything called ndisgdk.
One way is:
sudo apt-get install ndis-wrapper-common ndisgtk
You can also install packages through Synaptic Package Manager (under System/Administration).
System/preferences/Hardware Information should be installed by default, but may have been inadvertently removed if you removed something else, or just hidden in the menu.
If it's hidden, you can re-show it by right-clicking on System, and choosing "Edit Menus". Click on Preferences and tick "Hardware Information".
If the Hardware Information icon isn't there, then you need to install hal-device-manager. You can do this using synaptic or at the command-line:
apt-get install hal-device-manager