转自： http://linux.chinaunix.net/techdoc/system/2009/08/31/1133198.shtml
1.1 安装KDE桌面环境
yum groupinstall "KDE (K Desktop Environment)"
1.2 卸载KDE桌面环境
yum groupremove "KDE (K Desktop Environment)"
2.1 安装GNOME桌面环境
yum groupinstall "GNOME Desktop Environment"
2.2 卸载GNOME桌面环境
yum groupremove "GNOME Desktop Environment"
另一种方法：
yum groupinstall kde-desktop
yum --enablerepo=kde-testing groupupdate kde-desktop
yum update