Rollercoaster Tycoon 2 free?

I am trying to get Rollercoaster Tycoon 2 for free and I tried what "Sharky Gaming" told me to do found here: http://answers.yahoo.com/question/index;_ylt=AjVJhca._cz8BkEwGwzTBHPsy6IX;_ylv=3?qid=20110622212415AA7apa1 , but I keep trying to play it, and it keeps blocking me because I have no disc, please help me get around this, thanks.