Please read Linus Torvald's book "Just for Fun: The Story of an Accidental Revolution" http://www.amazon.com/Just-Fun-Story-Accidental-Revolutionar.... It mostly deals with his experience building Linux and the insane amount of work it took (he was a student at the time he wrote the first version, with the help of hundreds of other people via distributed development). It might give you some additional insight into the effort involved.