In first couple of hours after installing Kubuntu I managed to get it screwed by what it seems bug. Which is when on kde4, you play with visual setings. And on loading, you log in, and hear the welcome sound etc.. the picture hangs, and it becomes totally black.

I figured the best thing for me now would be to reinstall it. But how? On the same partitions I would like to reinstall it, I have Vista.. on the other partition. But everything was fine before I touched damn visual efects

It's a bug, probably several of them.

But KDE4 is still under heavy development (it literally changes from day-to-day, unlike MS), which is why no mainstream distro is yet shipping with KDE4 (+ "Bells & whistles") installed by default. If you choose to install it - fine. But you need to remember that it is still under development. By all means find and contribute to the KDE4 development forums and help iron out the bugs, but here on LQ, most of us are busy enough sorting out "I forgot my root password", "My printer doesn't work", "itunes.exe doesn't work" and the ever-popular "Helllllllp Meeeeee plz"

If you really want to be "bleeding edge", then go for it, check out sourceforge and recompile KDE4 daily, like the developers do, but I do not think this is the right place for you to complain when things "don't work" when you are using software that is still under intense development.

Linux is very different from windows - it develops daily and bug-fixes are released daily, until the component is deemed "stable" (though there may still be a few obscure bugs waiting to come to light when more people start using the "stable" software).

Yup, that fits.

If you want to play with (stable) linux, then just re-install your kubuntu 8.04 or whatever, and don't install stuff from "testing" or "unstable" (Do you understand the meaning of those words?), unless you are prepared to accept the consequences.