The Sims 2 on Windows 7?

I recently got a new computer (it is a little used) with Windows 7 on it. I got my old Sims 2 out, (I like Sims 2 better than Sims 3) I installed it, and ran it, but i keep getting a small popup that says : '' Please insert the correct CD-ROM, select OK an restart application''. What do i do now?