I have to revise my recommendation. I was just at Newegg and the 8800 GTS 512 (G92) is now $199. It's what I have and I love mine. It's a slightly better card than the 8800 GT and, as mentioned above it's a dual slot card that uses one slot to exhaust heat out the back of the PC. The 8800 GT just blows the heat into the case.
That's strictly by your under $200 request. At ~$150 now the 8800 GT is a great card for the price.
Regardless what you get, if it's NVidia, download RivaTuner and set your fan speed at a constant 65-70%. It will keep your card temps <50C, otherwise they tend to run hot (60C idle, 70C load).