I use Gnome, not KDE.
(Pause for flame war.)
However, there are a handful of apps that are designed for KDE that I prefer over the Gnome apps. But that presents one or two minor problems that can be easily fixed.
First a bit of background: Both KDE and Gnome are desktop environments, meaning, they are libraries and applications that serve as a kind of super-shell for using your Linux computer. Each has a file manager, each has a paradigm for how desktop icons and toolbars work, and so on and so forth. Beyond this basic stuff that one may reasonably think of as being part of your “system” (together with all the guts that that constitute Linux), there are additional applications such as graphics image manipulation, and so on.
If you use ONLY one or the other of these two desktops, you may end up installing the software libraries that facilitate that desktop. But if you want to run one or more applications from the other system, then when you install that application using a package manager, the libraries for that other system needed to run that application get installed as well.
This bothers some people. It bothers the people who can’t stand using disk space. Often, these are the same people who prefer
sed ‘s/blip/blop/g’ somefile.txt
cat somefile.txt | sed ‘s/blip/blop/g’
not because of glitches in cat, but because it uses two processes when one process will use the job. Well, I just went to the grocery store, and I used both feet, where clearly I could have hopped there and back on one foot. And, I’m using Okular (from KDE) as my PDF reader because I like it better than the Gnome PDF reader and thus KDE and Gnome libraries co-inhabit my hard drive.
Anyway, there is an additional difficulty in doing this: KDE apps (like Okular) look like KDE apps. Ick. And, things like font size in menus and so on do not pick up the settings I’ve already implemented for my Gnome desktop. This makes KDE apps both ugly and nonfunctional for me.
In the past, I’ve often had bot KDE and Gnome installed on the same computer, just for fun. This meant that the KDE settings utility was generally available for me to make the KDE apps look … normal. (I.e., look more like Gnome apps, and to have my font size settings, etc.). But with KDE 4.0, mixing the systems is actually a bit problematic (shame on KDE for making this so) and it does not work the way it used to.
But there is a way to fix that. From a terminal in gnome, one can install (apt-get) the KDE base package that has no apps but does include system settings utilities that will then show up somewhere on your Gnome menu (maybe under “system tools” in the app menu, or under “system -> preferences” … you’ll have to look around).
This is the command line you’ll want to use, if you are using a reasonably up to day (i.e, 9.04 or later) Ubuntu distribution:
sudo apt-get install kdebase-workspace
At some point you may be asked which default windows server you will want to us (pick the one that starts with “g” for “Gnome” and not the one that starts with “k” for “KDE”) and a whole bunch of crap will be installed on your computer. But good crap. You’ll be walking with two legs.
Then, go to the settings utility and fix up your KDE stuff to look good. At present, the only KDE app I’m really using is Okular for PDF files, but you might like to play around with some of the other KDE apps and utilities.
Good luck. Naturally, I take no responsibility for how badly you mess up your system by following my advice. And remember, Linux is not for everyone.