8800GTX memory bandwidth is 86.4GB/s (384bit)
8900GTX memory bandwidth is 105.6GB/s (384bit)

X2800XTX is 140.8GB/s (512bit) (if its real)

if the R600 MBus is really 512bit

even 8900GTX will be beaten by R600 in the high res+aa+af like *2048x1536 8xAA 16xAF

and the G81 should be totally re-designed to compete with R600 Rev.2