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.
Peace,
JimBass