I've decided to change the comment settings so that people not using TypeKey can still post, but will be moderated. I've also required that commenters leave an email address. Dont worry though, the email address is not visible on the site, its only available to me.
I've done this to hopefully keep any comment spam to a minimum. The people who make Movable Type list this in their Best Practices. I've also got a couple of plugins to install that help with automatically rejecting spammy comments and Trackback pings.