I can't decide between PS2 or Wii :(
PS2 has a huge variety of games which seem to never get old, plays PS1 games and plays DVD's
However the first version PS2 always crashed and, eventually, stopped working.
With the Wii you can connect to the internet, immitate the motions of the object you're "using" (Lightsaber, racket, bat, etc.) and you can download additional things to your Wii instantly.
However, it needs better games (Basically the whole purpose of a GAME system).