For anyone not familiar with the Disqus comment system, I would definitely recommend that you take a look at it. We are currently using the free version on several of our commercial sites, including this one.
The really great thing about Disqus is how easy it is to implement. This is true of both WordPress and MODx sites. Just create an account, add a few lines of code to your site and you are off and running. The administrative side is dead simple to understand and can easily be handed off for a customer to use.
