I couldn't wait for official Mandrake packages for KDE 3.4, so I installed 'Thac's Mandrake RPMs. On the whole it went OK, and my system was about 98% right. The remaining 2% was rather annoying though.
For the record, here's what went wrong:
'urpmi kdebase' (the one command to upgrade eveything) wouldn't work due to a missing dependency for something like libOpenEXR. After installing that everything else installed OK, which was fairly impressive as it was doing an upgrade of XOrg as well.
A missing dependency for kdebase-kdm (IIRC) meant that the login manager kept on seg faulting until I did 'urpmi kdebase-kdm'
Lots of KDE applications had messed up menus and toolbars - some missing items and lots of duplicated items
KHotkeys didn't import my existing (KDE 3.2.3) settings correctly (a pain, because I have lots of mouse gestures and keyboard shortcut set up)
Right-clicking in Konqueror induced a delay of about 10 second before anything happened, every time. The kind of bug that gets very annoying very quickly
Various other things, like a very slow trash:/ ioslave, certain menu items not working for the desktop menu, Konqueror's configuration tab being empty...
That's what you get for living on the bleeding edge.
So now I'm trying out Ubuntu (a new, well reputed Debian based Linux distribution), and I'm rather impressed so far. However, it's nearly 1:30, so I better go to bed if I'm to be fit to worship God tomorrow. Thankfully the Ubuntu installation took only 20 minutes, went without a slightest hitch, and enabled me to get my website uploaded quickly etc, so I didn't have to spend time messing around.
The GNOME installation is also quite nice (I haven't tried GNOME in a while). I can see why some people must really like it — and having a computer that is at least 10 times faster than the last time I tried GNOME does put it in a better light! But I'm not tempted away from KDE yet — I'll just apt-get install kubuntu-desktop and go to bed while it's downloading and installing everything.
Oh, one last thing — Ubuntu does an AMD64 build, which is what I'm using. So it's jolly fast, and it's getting the most out of my CPU for the first time, which is nice.