Is a particle board floor smooth enough to put laminate flooring down on. Existing floor has carpet and a matting underneath the carpet. Should the laminate be placed over the matting or on the parti?

Particle board is smooth enough to put a laminate down, but you also need to be sure the floor is level enough. Between each 4 x 8 sheet you could have crowning or also a raised floor joist can be the death of your new floor. Laminates are floating floors and are prone to problems when the subfloor has even minor humps or dips. Pergo requires floors to be level within an 1/8" in a 6 ft radius. I believe that is a pretty good rule to stick to. As to the carpet padding. It needs to come up and place down the manufactures recommended laminate pad. They are a lot denser then carpet pads. Also if you choose not to do so you have voided your warranty.