When you say extended, what type of keyboard is this? Many different multimedia keyboards are supported and can be found in the X-keyboard configurations. Additionally some that aren't supported can be mapped to work in X using xev and the x keyboard tools. If you are using 2.6 however, you will first have to make the keys emmit a code that X notices then map it to do something. Try doing a search on google for Linux and Multimedia Keyboards.
While learning to adapt, I am curious why my Linux keyboard doesn't support the extended section on the right. Is this normal, or is there a setting I haven't found? Not important, but I'm bored. chuck