Okay. I wiped the mandrak createde partitions, with Partition magic, thinking that I would start from scratch.
I moved the old "media" partition about a bit and made a bit more free space for Mandrake to gob up.
Took Partition magic about four hours to do.
After which my machine couldn't find the boot thing on my main drive (which shouldn't have been touched at all!). Strangely enough it found some strange Novell thing (which didn't get far).
So I quickly did a reinstall of mandrake, which installed a new Lilo, which luckily, could see both the old windows and the new mandrake partitions. Both booted fine and both could see my "media" partition.
BTW: I tried to boot knoppix on my old siemens notebook (350mhz pentium) - didn't work. Seems to be somekind of "cardmanager" problem, but it didn't help to disable the pcmcia detection, so I'll have to work a bit more on that.