if you want to run TheSims 2... go with Lukas' suggestion.
Trust me the GeForce FX 5200, 5500, 5600 and Radeon 9000, 9200, 9550 just won't run it quick enough.
They don't have the fillrate and/or polygon capabilities.
In-fact the GeForce 3, Radeon 8500 and GeForce 4 Ti will out-perform all of those cards without breaking a sweat.
The cards you want to buy really are going to be:
Radeon 9600, 9800, X700, 6200 or 6600
Try to stick away from the SE, XL, LE, etc. versions of the Cards. I'd also strongly suggest Ultra, GT, Pro, or XT versions of the cards.
Oh and for the love of god stick away from HyperMemory or TurboCache versions.