It will take up to a year before PS3 games come out that actually utilize the full capability of the system. I`m not saying that there aren`t games like that out now, but it will take some time for the majority of games to come to that level.
Xbox 360 on the other hand has been out for quite some time, and thus its games are taking full advantage of the system`s capabilities.
Yes graphics wise the PS3 is the superior system, but it also has the high price tag as well.
The Wii has the advantage of being the cheapest system out of the three, and thus will garner its fair market share. The Wii`s controller is its selling point, as it allows for user input that the other two systems do not.
In the end, I prefer the Xbox 360 over the other two systems. When all is said and done I think that the Xbox 360 will outsell the PS3 and Wii.
Halo 3 > All.