Sound proofing floor

Most of the advice posted above would spend your money for little result.
Sound travels in 2 basic ways....STRUCTURE BOURNE and AIR-BOURNE.
The trick is....the air-borne can become structure-borne and vice-versa.
Unless you TOTALLY decouple your new floor from the old, the STRUCTURE-BORNE sound will travel through.
Only an Acoustic Engineer can visit your situation and advise on the possible solutions.

I concur entirely with getting consul from an acoustical engineer, I needed to hear that from members, thank you.

Please inform us of the acoustical engineers advice. It will be interesting to look at the cost benefit ratio. Without going into specifics your idea of a 2nd floor islolated from the 1st is 'very' effective and I think you will find this confirmed by the engineer. (My father is an engineer)

Zargon, thanks for the info on the green glue. I'm doing some renovating and soundproofing for a suite and I'll definitely benefit from your input.