Do you have...
Assuming that you have all the Fedora repositories enabled, have you downloaded and installed the packages that are needed for KDE? If you installed Fedora with Gnome, Fedora will not automatically have provided more than what is required for that desktop.
Check your list of available package and the packages that are now installed, then you should see if you can use KDE.
If you don't set up your boot to require a log-in, you can boot, then do a log-out, log-in again, and you should be able to choose between any installed desktops.
Last edited by thorkelljarl; 12-06-2010 at 08:55 AM.