You can be confident nothing else will be erased ; however, unless you have deleted very important files and do not want someone to be able to recover them, there's no point in wiping the free space.
How thoroughly does CCleaner wipe your free space? I can't imagine it would be a thorough as something like DBAN(which I know whips your whole hard drive). I'm just curious how hard it would be for someone to recover information, if at all possible, after running the "wipe free space" feature in the program?