Roller Coaster Tycoon and Sims?

Wondering if I can get a free download of these that wont quit within a few minutes? I used to own different cds of these, but then I got a new PC and they don't work on it for some reason....and I do not wish to re-purchase them. And I tried a trial version download and it lasted all of like, 5 minutes! AH!!! Help please! Thanks!!!