This is properly the best free native 1.5 commenting system you are going to get for Joomla, I used it to install IntenseDebate which has been running on my site for about 3 weeks now.
It was dead simple to set up with just one plugin and the whole thing was up and running in less than 5 minuets.
It’s possible to control which articles have comments in the plugin parameters by either the menu and individual articles or by an extra plugin that is a comments button, which once installed, appears on the bottom bar of your text editor.
The only downside I have found is that IntenseDebate itself doesn’t allow much in the way of customisation; personally I’m fairly happy with it straight out of the box but if you read their forum posts, customisation and how to achieve it is always the main topic.
IntenseDebate also includes half a dozen or so gadgets to add to the commenting, including a most commented sidebar, but the one I really liked and am now using is the social networking links tab which allows visitors to link your article with any of the many social networking and other similar sites out there.
One other thing I particularly liked was that when notified of a new comment, the email notification included the option to moderate via a return email and also the IP address of the person who commented, which could be really useful if you needed to block someone for spam or abuse etc.
Thanks to the team at rockettheme for this great free plugin which couldn’t make adding commenting to a Joomla site any easier.

Amazingly simple to set up and use, I love the way it grabs the meta description and pictures from the page and then gives you a choice of which pictures to use (providing your page has more than one). Great work, thanks very much.
I didn't see a donate button anywhere on you site!!
Best Regards, Marty.

Great mod, dead simple to set up and you also get parameters to play with. Works every time even when tested locally, just need to figure out how to direct it to UK Paypal instead of US Paypal, not that it makes any difference to receiving donations, but for a UK site it would just look better in the browser address bar.
Nice one, Thanks very much.