Trying to upgrade dell dimension 4500 video card to play the Sims 3 what video card should i get?

I'm trying to play the Sims 3 on my dell dimension 4500. Every time i try to start up Sims it says upgrade video card with at least a shader model 2.0. what video card should i get? that will let me play not too slow and the card is not ridiculously expensive??

please help im not so good with computers.. thanks|||Any AGP card with 64Mb or 128Mb would be suitable, but that the system board won't handle higher-memory cards in excess of 128Mb.