the 285, 3800,4800, CX and 5800 are approved.
the 480GTX/295 also works with a minor hack.
you really should be looking in the Adobe hardware forum.
the 1800 has always been a joke of a video card with any of the nvidia gaming cards out performing it...
if you do more than 3 layers and time is money than the approved Quadros are recommended.
while a 285/480 are far faster than a CX,3800 or 4800 and equal to the 5800 (and the 480 is even faster) nVidia las placed a 3 layer limit on the gaming cards to force you into buying a quadro.