Comments Script

I'm looking for a script that would allow me to add a user feedback/comments feature to a product review site. I know Wordpress or other blog installation comes with this built-in, but I have an html site that's a few years old. So this would need to be a "bolt on" solution.

I was thinking of adding php pages to the site that the html pages would have a link to. Then visitors could load the php pages to either add or view comments.

Any suggestions would be most appreciated.

Thanks,
Rich