Sounds like you are trying to fly a 757 passenger jet when all you really want to do is pedal a bike across the road
You could go the route you are heading, and figure out which glibc/libc version you have installed:
rpm -qa | grep libc
Or you could use your distro as it expects you will along with it's package manager (urpmi, assuming mandrake of course).
Graphically it's called rpmdrake and can be launched from any graphical environment. But since you seem to be running into a snag getting to the gui, you'll probably want to use urpmi, the command-line equivilent.
You'll be in a little over your head, but not nearly as deep as if you go the route your were headed. You can probably optionally toss back in your install CD, choose 'upgrade' (might be called update, it's been a while since I've seen it) and choose to install KDE packages there to get them refreshed enough to get you into a gui.
Assuming that doesn't work, or you don't want to try that route, then read on.
So after you login at the command line (CTRL + ALT + F1) change to your root user:
And enter the root user's password. Now, we can give urpmi a whirl:
And see what gets returned. Alternatively, we can get something light running and then do KDE once we are back in the gui, so another window manager that may be helpful:
And lastly, if this is just a problem with your login manager (kdm IIRC) you can bypass it from the command line. Once logged in via the command line type:
startx -- :1
And see if you are able to actually get to a GUI via that route. If so, it's probably just a glitch in the KDM login manager and might be easily fixed by removing a corrupt file in root's home:
ENTER ROOT PASS
rm -r .kdm
And see if that gets it back on it's feet.
Hope that helps you head in the right direction at least, re-installing/installing KDE from scratch is FAR more work than one should set out for in this situation.