This recovery tool is not useful because the format of the Asus disk is not EXT2 or EXT3, but ReiserFS. You can see it as NTFS or FAT as is used by Windows, but it is of course not the same. It is the way information is stored on the disk.
They are provided to prove to you that the iso file you downloaded is intact and not a falsification.
I think that when you burn the DVD your software will tell you the md5 or sha1 fingerprint so you can compare this to the ascii files. It's a matter of trust.
Okay, first, MBR stands for Master Boot Record. It's just the very first 512 bytes of a disk. It's not Linux specific, just a computer term. Google for it and find out.
Second, dd uses 'if' for Input File, and 'of' for Output File. In the instructions you see only a filename without a directory (asus-mbr-original), so this file goes where you are. Probably in the home directory of your Knoppix session. But you must make sure you KEEP this file, and Knoppix is just only there as long as you use it. You could try a floppy (fd0) or a fat partition on your pc's hard disk. But you need some understanding of the way Linux sees floppies (fd0, fd1,...) and hard disks (hda, hda1, hda2,... hda5 etc).
Remember, if you don't need to use the disk in the Asus anymore, there is no real need to keep the original MBR for restoring.
With FDISK you will write a new MBR, one that is usable for Knoppix, but unusable for Asus. As said, this information occupies only 512 bytes, far out of the way of your own data, that will not be touched.
You will see it with names of course. Just as the screenshot in my original posting, or similar. At least, so should it be.
Marc