I know I am a little late in replying to this but have not looked for some time. The others who have answered are correct that it is easy to take the train to Amsterdam from Schiphol. There is a website which describes such a visit at: http://tinyurl.com/45xd7

However there is also a tour company that actually has tours starting and finishing from Schiphol. http://tinyurl.com/5b78u

I hope this still helps and is not too late.

Cheers, Gerrit in Perth Western Australia