I'm pretty sure of this:
Don't know about the GUI partition tools but cfdisk and fdisk (from slack) can see all hidden / restore partitions I've ever encountered. And there's no reason the other distros' partitioners can't either, so if you're just wiping the drive,
"pop in the Mandrake 10 disk 1 and it'll boot, partition and format"
ought to be about right.
Just tell it to delete the old partitions, all of them, first.
Oh yeah, just a tip, I'd make sure everything works under Linux before wiping everything else... if you didn't already check, that is. I hate laptops sometimes; you will too, if you skip this step and have problems
This info is from someone who has experience with only Slack, mind you.