360 will have major advantage in terms of sale over any next generation system for the sheer reason that humans of no patience. Xbox 360 is currently supposed to be released fall 2005. while the revolution and PS3 will all be later in 2006 (Sony will do the usual "release in japan, then bring it to US half a year later")
These new systems arent exactly cheap so by the time everybody already owns a xbox360 will anybody still buy a PS3? (well yes, but will they perform well?)
on a side note: Kingdom Hearts II is set to be released november 2006!!! (THATS AWSOME!!) I FUCKIN LOVED the first 1 except for its camera which is said to be improved. Also, it was said (some magazine reviewers played japanese demo) that they managed to make a better fighting system and also, the gummi ship wont be as crappy. On the plus side, square managed to load up a shitload of enemies in this disk, and made it good quality too (its released for PS2 not PS3)