the X1950 pro is the fastest for AGP 8x
next in line is the 7800GS and 7600GT...they are nearly identical in perfomance...the 7800GS overclocked will perform closer to a 7900GT.
Australian and European customers do have access to the Gainward series 7800GS+ cards which feature 7800GT, 7900GS and 7900GT cores instead of the 16 pipeline 7800GS core, they are considerably faster than the standard 7800GS.