Underlayment options for laminate flooring.

My question is in regards to laminate wood flooring underlayment. The photos at the following link explain it best.
<a href="http://members9.clubphoto.com/eric472999/2441265/guest.phtml ">Photos</a>
In the photo you are looking at the center of the room that has a 4x4 support post. This where 3 different types of floor merge together. A parquet wood floor in the dining area, a vinyl floor in the kitchen, and butcher paper(stop gap) over 3/4" plywood, where a carpet use to the exist. The plan is to replace the parquet and vinyl with the same laminate flooring. The question is in regards to underlayment. Under the parquet is 3/8" particle board and under the vinyl is 1/2" particle board. The particle board is nailed down, not screwed into the 3/4" subfloor. Should we do:
a) leave the 3/8" particle board and put down new 3/8" particle board to match the height
b) Remove all the existing particle board and replace with either 1) the best foam underlayment that the laminate floor manufacturer provides 2) no underlayment, just a moisture barrier on top of the 3/4" plywood. 3) cork (4mm) underlayment 4) Quickstep 1/4" softboard (.30/sq ft.)
c) Use new and inexpense 3/8" or 1/2" particle board screwed down.
My biggest concerns are sound and trying to achieve the solid like feel of real wood with this laminate floor.
The laminate floor is the Harmonics from Costco which I hear is the Quick-Step white box stuff. 8mm thick.
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