If you're doing a fresh installation and you don't have a CD downloaded yet, I can recommend the netboot installer. It let's you download and install the freshest packages from a mirror near you. All you need as preparation is e.g. a USB-Stick that boots into grub. Checkout this howto.
Basically all you need to do is copy the kernel "linux" and the initrd "initrd.gz" to your stick. Then boot them from Grub and you can start your installation.
The great thing about it: During the installation you can chose whether to install Kubuntu, Xubuntu, Ubuntu, etc. And you will automatically get the newest available packages right away. There's no need to fetch and install updates after the installation.
And getting the newest packages right away might save you a lot of trouble because of bad packages in the installation cd. And the network installer itself also gets updated regularly.