|Your video chipset is not supported in Sims3. If you could get it to work, the results would be very disappointing.|
It gets worse...your power supply is, I believe, 250 Watts and that will severely limit what aftermarket video card you will be able to install. I'm not sure if an off the shelf power supply upgrade is available.
If you are able to upgrade the power supply and video, the price tag will be $100-150. If a non standard power supply is required, this will all get even more expensive.
Your problem is typical of folks who spend 300 bucks for a machine and want it to do the work of a $700 pc.