I’ve been playing around with KDE4 flavoured Linux distributions for a couple of weeks now: I’ve tried various betas and release candidates of Kubuntu, Fedora and openSUSE. And I must admit, I like openSUSE the most. Downloaded the live cd, and installed from there on without a hitch. Installation was very easy and straightforward. The only thing I did afterwards was installing Pidgin as instant messaging program, and the VLC media player. openSUSE is much more vivid and responsive on the same sytem than Kubuntu and Fedora.
On a side note: this was the first time I installed a 64 bit operating system, and I’ve had zero problems so far. Flash was easily installed from the non-oss repository and runs smoothly.