Looking at the official Sims 3 systems requirements, your GeForce 6200 is supported. Therefore, do what was recommended above.
1. Update DirectX. The Sims 3 DVD should have it on the DVD (like most other games).
2. Update your video card's driver to the latest version that supports it. I'm pretty sure nVidia officially stopped supporting the GeForce 6xxx series since it is pretty old. Go to nVidia's site to find the most recent supported driver.