Well... how long is it going to be until you have money to purchase new games?
I mean, if you're on a tight budget you may want to go with the Wii+PSP, or even just a Wii or PSP, just for the variety of games.
I mean, if i was just stuck with two games like Resistance or Motorstorm for more then like 3 weeks i'd go crazy. (By games like motorstorm and resitance i mean not RPGs/Strategy games, games who's playthrough times are huge.)