Need best possible video card for Dell 8400

[SuperVisor]

My 1.5 year old ATI Crossfire x800 just died. Pretty bummed as I would expect the card to last a lot longer. Anyways, looking to get the best card possible without having to replace the stock power supply on the Dell 8400. I believe it's rated at approx 350w, but will need to verify. I heard Dell was pretty conservative when rating their power supplies so I may be lucky and can get a decent card. My wife plays Sims 2 which seems to be a hog. I play some older games...not the latest ones. I would like it to be as future proof as possible though. Looking at ATI or Nvidia chipsets...not that picky. Hoping to spend about $100, but flexible. Thanks in advance.

 

[winnar111]

4850's have worked ok on the new Dells.