Well, my attempts to check the data integrity of my Ubuntu installation file did not go well. The Ubuntu website strongly recommends the procedure before burning the file to CD. I can definitely understand the need for your OS install CD to be 100 percent correct, so I followed the instructions for downloading and running the md5sum utility that are located on the Ubuntu website. I tried downloading an md5sum from a couple of sites, actually, and the result was always the same: my computer never recognized the md5sum command.
So now I have a dilemma. Do I just burn the CD and hope for the best, or do I keep trying?