In fact you don't need libpython-devel.
You need a package called simply python-devel
Unfortunately you can't find that because mandrake gives this kind of package only into sales OS or to registered mambers of Mandrakeclub.
I've left mandrake for suse due to this limitation.
You can have what you want if you pay.
This is Mandrakesoft policy.
You have only a way.
Try to download python-x.x.x-src.rpm (were x.x.x is the version of python you've got) and make the package by yourself using rpmbuild --rebuild.
Be aware that sometimes mandrake package are reduced version of the original package and it can contain only python that you also have without development package.
Let me know
walker