We are looking to install 3/4" solid hardwood. Unfortunately the subfloor is Partical Board from the 1960's so by just looking at it initial you may think it was OSB. Nonetheless, I heard through a friend/contractor that he knows of other installers that encounter this problem quite frequently and they have a "new" method that will supposedly solves this problem.

He claims what they do is nail into the stubs whereever possible and where there are no studs they nail into the subfloor at a severe angle to prevent the nails from popping out or loosening. I am still skeptical and pose this question to anyone who may know more about the subject.

I also have asked another friend who installs hardwood floors about this method and he said he wouldn't do it if it was his house.

I've also considered making certain this contractor/installer would guarentee his work but the last thing I want is to have replace the floor all over again!

Any thoughts/comments on this "new" method?

Please read this:
http://www.hardwoodinstaller.com/hardwo ... .php?t=385
First, you need to determine if the particle board is truly the subfloor or if it is underlayment.
Then, remove it if it is underlayment. If it is subflooring, as you say, then, according to NOFMA and the NWFA, you should install 1/2" CDX plywood underlayment over the particle board as a nailing base. If the subfloor is 3/4" thick or more, very little of the 2" fastener (cleat or staple) will actually tag the floor joist because of the 45 degree angle of nailing T&G flooring down. I have a particle board (Red X) subfloor in my home and installed 1/2" plywood first before installing my oak flooring.