today i installed kde 4.0 on my kubuntu 7.10 besides kde 3.5.
I wont say anything about the install procedure googling will
find you a lot instructions.
Everything went fine on my install, but when i wanted to login
to the new kde 4.0, all i got was a black screen and i returned
to kdm.
Hm, a lot of trial and error didn’t get me further so i asked in
the kubuntu-kde4 channel on irc.
And somebody really knew what problem i was sitting on.
I have an nvidia graphic card and used the binary drivers from nvidia.com
which where a little bit outdated at that time.
So i installed the new drivers from nvidia, which worked flawlessly and
see, everything works fine now.
And they made a huge effort with kde 4.0 it is what they said it would be,
a really new desktop with a huge lack of kde apps that have to be ported
to the new qt4.
But what works, works great, for me and i can use the old kde 3.5 apps
under kde 4.