In Konqueror: Settings Menu -> Configure Konqueror -> File Associations -> Application -> PDF
If kghostview is listed but not first, move it up in the order using up button.
If kghostview is not there, click add and add it.
I just checked Mandrake's site and kdegraphics-kdf is the right file name.
Could be your urpmi sources aren't configured right.
If you can mount your Mandrake CD, go to directory containing all the file ending in rpm. ( I think it is i586/RPMS)
And type
Code:
rpm -Uvh kdegraphics-kpdf-3.2.3-16mdk.i586.rpm
That should install it.