Hi Jlobel,
Could you be a bit more specific? Are you having trouble getting Linux to boot, or are you having trouble logging into KDE4?
The operating system (Linux/*BSD/etc.) and the graphical user interface (I should say 'desktop environment'...; KDE/Gnome/etc.) are 2 different things on unices.
(Actually, they are also 2 different things on Windows, because Windows should not be called an operating system, but that's an entirely different discussion...)
Also, when you reply, tell us which distro you installed.
Rob