I finally fixed up some things on my site, which will make it easier for visitors to comment but stop comment spam.
Before today, to post a comment, a visitor had to register as a user. The user would then be required approval (since comment spammers create dummy users to gain access and post). I wouldn’t have time for this so that alone would take months, then finally the user could login and post.
Today I cleaned out the database of these dummy users, installed Drupal 4.7.7, and set-up a captcha (Drupal’s Captcha & Textimage modules). Anonymous users may now post comments only after solving the capcha, and their comments require approval. Registration requires solving the captcha, but doesn’t require user approval, and doesn’t require approval nor solving a captcha to post a comment.