Locking down comments

I just can't take it anymore. Even with all of the anti-spam measures in place on my MovableType site, I'm still getting inundated with hundreds of spam comments a day, and am missing too many comments I want to read by either accidentally deleting them or missing them in my junk pile. So, I'm doing the only thing I can to keep comments flowing while not ripping my hair out trying to deal with the comment spam problem here, and that's requiring comment authentication.

I'm sorry for the extra step that will be required for leaving comments (LiveJournalers, obviously, this won't affect you :)), but it's necessary for my sanity.