Before you get too excited about this project, first, you need to do some research.
You need to find a floor to float, and then you need to read the installation instructions to see if the floor is OK'd to be floated above the concrete. Your question leads me to believe that you're thinking you can float ANY hardwood floor. No, you can't. In addition to reading the installation instructions to see if the floor can be floated AND installed over concrete, do read the warranty too. There may be more in it about your 'application'.