I've not played Z&W myself, I just thought it looked fun and I ehar it really is. Perhaps Rayman would be better then, but I seem to remember from the "2d" days of Rayman that those games can be quite hard as well?
Anyone tried it and know?

 yeah, but every game from RRR series is a party game with freaky minigames with adorable rabbids;)

By nearly double if I remember correctly. PS2 production at it's highest was like... 1 million a month if i remember correctly. I'll try and find something to back that up though.

Funny thing was that Sony said they were set up to produce 1 million PS3's a month from launch because they thought it'd be bigger then the PS2.

Edit: ah wait. 1.3.  At one point they were producign 1.3 million PS2s a month... or at least planned to... no clue if they suceeded on said goal. 

What about Twilight Princess? Not too difficult really. If she like puzzle solving and doesn't mind a game where you get stuck every so often than I'd say this would be a great bet. Or wait until Mario Kart comes very soon. Mario Kart is never than difficult on the single player.

SMG is easier than Sunshine (at least to beat the game, getting all 120 stars can be a bit difficult at times but still easier than Sunshine's hardest Shines imo). If there's a lack of controllers than why would you get a primarily multi-player game?

I was going to be cheeky and recommend something like Mortal Kombat Armageddon, but that'd be just mean. For other lesser-known fighting games though I hear Naruto and DBZ are actually pretty good.

Super Paper Mario could be a good fit too, as long as she's not afraid of reading.

Considering Nintendo just set a record last month for most systems sold (outside of launch/holiday), I'm not sure I can really blame them for it still being sold out; it's not like they're not putting systems out there.

Hahahha Wiiniece.... XD Sorry I'm stupid LOL. I'd totally get Smash brothers or Mario kart :P but maybe thats just me >_>;;

Well, maybe your niece can play SMG now, I mean she is 10... she was what 4? 5? when SMS came out... And SMG is very easy for the first 30 stars or so.

I played Sunshine with her last year.

Get her something that will allow her to understand and appreciate gaming. You're going to want her to have a great exerience that keeps her into games. I say Zelda Wii or Smash Brothers.

Well your getting it for her birthday so how bout Mario Party 8? Makes sense right?