Take seriously on this topic
we all know, HD 2900xt was good In 3Dmark,especially in Crossfire mode
Nvidia Leads SM2.0, ATI gains lot at SM3.0/HDR
those two makers won their advantages in 3Dmark
beside 3Dmark06,ATI Leads '05 , Nvidia takes crown in '03
for those 2 different kind of architecture,it's hard to compare per clock performance

i got this 8800GT yesterday
after a brief testing, G92GT is so awesome in 3Dmarks
so, i going to compare with those 2 cards, 8800GT vs. HD 2900XT
have no mod ,and all wear in stock HSF
so for this session, try the max stable clock in '06 from those 2 cards

for Albatron 8800GT, get 737Mhz-core,1782Mhz-Shader and 947Mhz (affective DDR3-1894)
set all test bed the same,only swithed vga card,8800GT installed forceware 169.04
and HD 2900XT has Cat 7.10

Albatron 8800GT, get 737Mhz-core,1782Mhz-Shader and GDDR:947Mhz (affective GDDR3-1894)
3Dmark '06 Scores 15873p


and the other side of Sapphire HD 2900XT ,874Mhz-Core,981Mhz Memory(affective GDDR3-1962)
3Dmark'06 scores 14693p


final word: nvidia brings vga card to new battlefield with G92
HD 2900xt has pasted away