Someone could tell me that the best way is to download and see... but I don't have a sufficiently fast network...

What is the difference between

kernel-source-2.4.22-30mdk.i586.rpm

and

kernel-2.4.22.30mdk-1-1mdk.src.rpm ?

Both should contain sources, am I wrong?

kernel-source-2.4.22-30mdk.i586.rpm will install the kernel source in your /usr/src directory, ready for you to compile.

kernel-2.4.22.30mdk-1-1mdk.src.rpm if I'm not mistaken, will produce an rpm similar to kernel-source-2.4.22-30mdk.i586.rpm (depending on which if any complile flags you use) which you will then have to install.

In other words, wait for a more experienced user to explain lol.

sttroopers is essentially right.

The kernel-source rpm installs the kernel source code (and usually any patches) to /usr/src

the kernel.src.rpm installs the source/specfile/patches etc required to build the Mandrake kernel into an rpmbuild directory on your machine (mines in my ~, but this isn't default), from which you can build a binary rpm to install the kernel.