I've not played the new playstation yet. I understand that they are quite expensive.
The Wii I believe is much less expensive but the games tend to be more of the family friendly variety and the Wii can not play dvds or blue ray as far as I know.
I got playStation3, it's good, a lot of games available, and certain games monopolized by it, like Metal gear solid [I bought it 2 years ago]. but why would you prefer Xbox! [I may get one]