Many distros come with both KDE and Gnome, and default you one way or the other. You can always tell the installer which to use. Back when I used Fedora, during the install it selects Gnome, but I would always change it to KDE, and it installs just fine that way too. Kubuntu is the debian based ubuntu with a KDE desktop rather than Gnome. You can also find out all the default desktop enviornments by checking out this link --http://en.wikipedia.org/wiki/Compari..._distributions
Towards the middle of the page they show most distros with default desktop, but again, you can "usually" install any desktop you choose right from the install disk.