I like KDE4 quite a bit. I love Dauphin over Nautilus. But I've always been fond of Gnome's Evolution mail suite over the KDE offerings. Really, it's a matter of preference and I recommend trying out some LiveCDs of various distros before actually installing anything.
whats the real diference between all this linuxes... Fedora.. Ubuntu.. Geetoo... and such???
Preferences, loyalty, package management, look-and-feel/branding, community support, sometimes even retail support (Dell's Mini9 has a special version of Ubuntu installed).
Ubuntu (based on Debian) is definitely geared towards the linux newbie. Easy to install the distro and programs, easy to update, huge community support, etc...
Like I said, I like KDE4 and I prefer Opensuse 11's implementation of it. I also like the Yast configuration manager. Their community seems to be steadily growing and the distribution is really becoming solid. Still not quite as fool-proof in some areas over Ubuntu (distro upgrading or installing), but I think their desktop implementation is more intuitive. It also gets a few benefits as plays a little nicer with Windows networks, for example, since it's a child of Suse Linux, which was bought by Novell.
Fedora is somewhere in between Ubuntu and Opensuse.
Gentoo is much, much more complicated to install. The idea is that absolutely everything is compiled for your specific hardware, which should have performance benefits. In truth, I think it's wasted time and effort because the benefits are pretty much imperceptible, and you're not really learning all that much about the linux system during install. If you want an educating experience during install, then go with linux-from-scratch.