Harry, thanks for your experienced advice and patience with first-timers like me.

These are simple measures to ensure successful CD/DVDs:

1a) Use the torrents rather than the mirrors
Yes, this is the best option. Using a torrent does not eliminate errors though, as I discovered. Whether by user error or otherwise, my 'uTorrent' download was incomplete even when it said "finished". I had to re-check/re-start my download.

1b) Do the simple md5 test
Yes, this step should be mandatory after a finished download. Foolishly, I ignored this hash key verification and trusted my torrent application to verify the complete download.

For an explanation of the procedure, go to:
http://www.knoppix.net/wiki/Downloading_FAQ#Q:_What_are_these_strange_MD5_file s_that_accompany_the_ISO_CD_images.3F

It's a single command:
Code:
md5sum -c KNOPPIX_xxxxxxxx.iso.md5
Here is the erraneous output after my first attempt of the uTorrent download:
Code:
md5sum -c KNOPPIX_V6.2.1CD-2010-01-31-EN.iso
md5sum:   @@@@@@@@@@@@@@@@@@@@@@@@@@ : No such file or directory
  @@@@@@@@@@@@@@@@@@@@@@@@@@ : FAILED open or read
md5sum: int1e = %08x: No such file or directory
int1e = %08x: FAILED open or read
md5sum: WARNING: 2 of 2 listed files could not be read
Here is the successful output after I 're-checked' and 're-started' my uTorrent download:
Code:
md5sum -c KNOPPIX_V6.2.1CD-2010-01-31-EN.iso.md5
KNOPPIX_V6.2.1CD-2010-01-31-EN.iso: OK
Knoppix is working and an important lesson learned.