Helping people with computers... one answer at a time.
The Sims 2 may not work for a number of reasons, but there are a few things to look into to make sure the game is compatible with your computer.
Why can't I get The Sims 2 to work on my machine?
I'll be honest, I don't know. People are reporting various problems getting The Sims 2 running and getting DirectX 9.0c installed on their machines.
I do have several resources and what appears to be the most common cause of problems.
The biggest cause of problems running The Sims 2 appears to be video hardware and software related. Specifically:
There's an overview article on The Sims 2 Bulletin Board: Video card problems/Direct X error of non-compatibility issues that covers all these steps and has links to much more detailed information. That bulletin board is also the recommended place to go for support and additional information relating to The Sims 2.