http://www.anandtech.com/tradeshows/showdoc.aspx?i=2423&p=3
i dont think anyone would call anandtech a biased site. Their hardware reviews have always been top notch.
"Given that the RSX is based off of NVIDIA's G70 architecture, you can expect to have a similar feature set later this year on the PC. In fact, NVIDIA stated that by the time PS3 ships there will be a more powerful GPU available on the desktop. This is in stark contrast to ATI's stance that a number of the features of the Xbox 360 GPU won't make it to the desktop for a matter of years (potentially unified shader architecture), while others will never be seen on the desktop (embedded DRAM?)."
"NVIDIA stated that they will eventually do a unified shader GPU, but before then there are a number of other GPU enhancements that they are looking to implement."
In other words ,
_RSX' performance is below that of Geforce 7800 (the top of the line nvidea card for the next gen months)
_Xenos' performance is higher then that of the upcoming r520
(case in point, ATI had the r520 ruby demo easily running on x360 gpu at e3, with effects and resources to spare)
_Nvidea is already looking into copying ATI's aproach for their g80 or whatever itll be called
so much for PS3 beeing "twice as powerfull" as x360 eh