I'd suggest doing an archive&install. You'll get all the benefits of a clean OS install and fresh system/library folders. You can even get a clean profile but not choosing to preserve user accounts (they are saved, but are then in a folder that the installer creates called Previous Systems and you just copy the iTunes, iPhoto, etc. data folders/packages into your new profile.
I think he/she has the original media, but the question is about where to save the data files to, hence my suggestion of an archive&install instead of an "erase"...
Unless you installed some sort of system level files beyond Apple updates the majority of your files that you consistently create or modify would be in your user home directory.