If I bought a used computer, the first thing I would do with it would
be to reinstall the operating system cleanly. You have no idea how the
computer has been maintained, what has been installed incorrectly,
what is missing, what viruses and spyware there may be, etc. I
wouldn't want to live with somebody else's mistakes and problems,
possibility of kiddie porn, etc., and I wouldn't recommend that anyone
else do either.