I've been using an rpm-based distribution for years and never found a great deal of problem.
Here's an easy way to figure out what you need to satisfy those dependencies:
Go to
http://rpmfind.net. Enter the filename of a required file in the seach box and hit enter. I did this for libkdecore.so.2
The search results page shows rpm's supplying this file, for different Linux distributions. It seems the rpm you need is "kde1-compat-x.x.x.rpm".
Perhaps the rpm you are trying contains software designed for the kde v.1 desktop environment -- and your using v. 2. The "kde1-compat-x.x.x" rpm will probably provide backward compatibility.
I don't see a specific Mandrake version there. Look to your CDROM(s) for a "kde1-compat-x.x.x.rpm" file, or something similar.
...Another thing just occurred to me: go to where you got the original rpm you're trying to install and check to see if there are different versions for KDE 1 vs. KDE 2. If so, get the version for KDE 2!