Soundproofing underlayment recommendation

We have used this:

http://qtsoundcontrol.com/

I just had a new hard wood floor installed with soundproofing as per building regulations. They used what Primer05 recommended.

We installed new plywood subfloor then the QuietWalk underlay from Lumber Liquidators then new solid floorboards installed on top of this. Fantastic difference.

Cant hear a thing from the apartment below us (they also don't hear anything from our apartment apart from when someone drops something directly on the floor).

Well worth spending the extra money on new subfloor/underlay/boards, I don't know why people in NY continue to complain about neighbors when for just a few thousand dollars the noise problems can be solved for good.

BTW if you want to save some money I have a entire 100 square feet unused roll of the underlay here for someone who doesnt mind making the effort to pick it up from Brooklyn heights - http://newyork.craigslist.org/brk/mat/4343881512.html