do you have a broadband connection?
because if you have one, you should/must set up your urpmi-repositories. the easiest way to do that is follow the instructions on
after doing this, go to your mandrake control center, remove your dvd from your repositories. now you can install additional software without using your dvd (by using your mandrake control center (it also works in the shell with the urpmi <package-name> command (as root)(sorry about the amount of () ;-)).
if you dont have broadband, i will have a closer look at your problem and answer tomorrow again
look at this thread too: