The Sims does work on Windows XP and you don't have to do anything. If you want it to work on Windows Vista and Windows 7, you have to right click on the icon and run it in compatibility mode with windows XP.
I forgot to put up in the description box but then whoever win, have to contact me by 3 days or else it will be back up & I'll keep the credits! So, make sure you contact me!!! Thank you!