Half-life 2, FEAR and all other game were tested are known to run better on ATI
If you look at the benchmark for Supreme commander oblivion and STALKER, the 8800GTS beats HD2900XT
AMD's Radeon HD 2900 XT graphics processor - The Tech Report - Page 11
So, in other words HD2900XT is barely faster than 8800GTS, and it is more expensive, consume much more power, and produce a lot of noise
One says the card can't even keep up with performance with a 8800 GTS 320 while the other says the R600 can beat the 8800 GTX in some cases!?! One of them is right...the other is wrong...we need to find out which
It depends on which game you are comparing.
For example, in STALKER 8800GTS 320MB beats HD2900XT
In other games like FEAR, HL2 the HD2900XT can beat 8800GTS 640MB
But no, the 8800GTX can destroy R600 in almost all cases.
Just look at your own benchmark. GTX performed better in all cases