Orbilius

Advice Needed

All of my blogs (Dr. Weevil, Curculio, Write It Right, and a couple of dormant spin-offs) are being inundated with a flood of comment-spam. Yesterday alone I deleted 200 comments from Dr. Weevil. Between the dial-up connection, the 6 1/2-year-old computer, and Earthlink's sluggish host-machine, it took over three hours.

I have turned off comments on all of my blogs except this one until I can come up with a foolproof spam-repellent. I'm using this one because it only has the one post, so any number of spam comments could be deleted very efficiently.

Advice is much appreciated, but please read these provisos first:

1. Call me cheap, but I don't want to spend any money.
2. If at all possible, the method has to work on MT 2.0 and 3.0. Though I don't recall the URLs, I've read more than one site-owner complaining that an MT upgrade had wiped out all his comments. I don't want to risk that, and have stuck with the versions I began with (2.0 for Dr. Weevil, 3.0 for the rest).
3. Closing old comments doesn't seem to work. I have used the MT Editing menus to close hundreds of comments 'by hand' on both of my main sites, that is, I have unchecked 'allow comments' for each one individually. Nevertheless, spammers continue to leave comments on all of them.
   (I even get comments attached to posts I haven't written yet. I don't know how that can be possible, but it happens. When I go into the Editing menu and delete a comment, I am taken to the post to which it was attached. About a quarter of the time, that post is blank.)
4. I don't want to install a complex registration system. There are some sites I rarely visit any more because I've been unable to figure out how to leave a comment. I don't want to be like them.
5. I would like to ask the commenter to type in a number displayed as a picture, so spam-spiders can't read it. Can any of my readers tell me how difficult this is to implement, and where to find the software?