If those are the CPU speeds you're dealing with, forget Mandrake - it's got too much "eye candy" for slow machines. (So does Knoppix, for that matter.) Debian Woody sounds like it's a better fit (if you can live with KDE 2), especially for the 133.

You can get an idea of what the (text-based) install process looks like here, although it's a bit different for Woody than Sarge. Of course, there's a comprehensive installation manual available.

Again, the biggest thing that Mandrake has going for it is its easy GUI-based installation program. Debian assumes you can figure out how to use cfdisk to partition your hard drive; it assumes you know what hardware you've got, so you can choose which kernel modules to install; it assumes you can use dpkg to select which packages you wish to install. All of this is done via a text-based interface which might be intimidating to first-time Linux users.

So maybe your real best bet is to grab an older version of Mandrake, install it, use it until you get comfortable, then wipe it and start over with Debian.