My quick list, slowest to fastest (a slash indicates essentially equivalent cards):
9000/9200
FX5200 (faster AA than comparable ATi cards)
9000 Pro
8500LE/9100 (memory speeds may dip as low as 200MHz; should be 250MHz)
8500
-------> below this point, ATi cards lose less performance enabling AA & AF, and look better doing so <--------
9600 (not sure about this, but I believe a 9600 is faster than the 8500 series w/o AA & AF)
9500
4200
4400/4800SE
4600/4800
FX5700
9600 Pro
9500 Pro
9600 XT ~ FX5700U (though 9600XT will be faster in DX9)
9700
5900SE/XT
5900
9800
5900U
9700 Pro
9800 Pro
5950U
9800 XT
Aim for 128MB. I'm reasonably confident in the ATi order. It's tougher to integrate nV into the chart because nV's FX cards tends to fall off faster with AA+AF vs ATi's DX9 cards, and I still believe the FX line will be slower than ATi with DX9 effects (though you can always just turn off DX9 effects).
Again, check the Digit-Life and NordicHardware articles I referenced in your Ars thread. This sort of list is always imperfect, as the cards can change performance order depending on the game and the extra filtering. Really, your best bet is to read as many well-done reviews as you can to find benchmarks relating to the games or genres you'll be playing.