worse case for Xbox2:
I'd expect PS3 to be *upto* 3-4 times more powerful, on paper, and in theory, than Xbox2. that is still less than the difference, on paper, bandied about between PS2 and Dreamcast. PS2 was touted to be, conservatively, 4-5 times more powerful than Dreamcast, and upto 20 to 50 times more powerful than Dreamcast in certain areas. like, remember, 50 times more image data.
even *IF* PS3 was 3-4 times more powerful than Xbox2, it probably would not mount to much difference in first generation games. and even in later generation games, it will take PS3 developers quiet alot of effort to show a noticable difference over Xbox2.
look at Xbox and Gamecube. the Xbox is newer technology, and is several times more powerful than Gamecube on paper (going by PR spec anyway). but the difference between them in games is not so huge.
likely outcome:
I'm expecting PS3 to be maybe 2-3 times as powerful as Xbox2 in CPU power but only 50% more, or at most, 2x, in GPU power. the GPUs are going to be fairly close. PS3 GPU should have some more performance to play with. higher fillrate, higher bandwidth, higher rendering throughput, but not nearly as much of an advantage over Xbox2 GPU as there was between PowerVR2DC and GS performance difference, which was hugely in favor of GS. (not talking features or image quality, which favored DC's CLX2 / PowerVR2DC) ....Features wise, the PS3 and Xbox2 GPUs should be very close.
some people are probably still thinking that PS3 will outclass Xenon in CPU power by an order of magnitude. like 10 fold or more. they are probably thinking 1TFLOP / 1024 GFLOP PS3 CELL 'BE' CPU vs 84-100 GFLOP Xenon CPU. ....and then a PS3 GPU that outperforms Xenon GPU as much as the PS2's GS outperformed the DC's CLX2 / PowerVR2DC. this is just extremely, extremely unlikely.
I will eat the worlds population of dead crowe corpses if this happens.