haha, i had the same problem but i could not unmount my harddrive.

the way you install knoppix is very important. the best tutorial you can find is here:

http://www.irongeek.com/i.php?page=videos/knoppix1

keep in mind that if you don't have a linux swap file, you may get nothing but a black box on a background. if you do, start the kernal by typing in order:

"sudo -s"

"knoppix-installer"

this will fire up qtparted,which you can use to partition and fix your hardrive, then setup your installation.

if worst comes to worst on your hardrive, download killdisk on another computer, save it to a bootable floppy, and run it in your computer. you can start from scratch and you should have no problems then.