Well, this topic is a bit old, but as it ends on a question, i'll give it a go.
I suggest you first try a live CD with KDE4 before installing it. There's Fedora
, and some others.
As you've been warned, it's not finished yet, so if you hate it, it's normal
Concerning the installation, if you're asking such questions, i assume you're pretty new to Linux.
The short answer would be "don't do it" because it would very likely break stuff in your system.
However, if you're feeling adventurous, you can find instructions on the KDE website
Same answer for upgrading Daryna with Hardy repos, "don't do it"
Elyssa KDE CE should be out soon (i'd say roughly less than 2 months), so a bit of patience never hurts.
Once again, if you really feel adventurous and are willing to break your system, a bit of searching through these forums should give you the answer.
As you can see, i don't give you direct pointers, this is intended.
Now, be very
polite if you come in 2 days asking for help to repair your system..
I guess this is it.