Wii at launch for me with a few games.
Zelda is a must and I'm pretty sure I'll check out Red Steel.
The third is a toss-up between Trauma Center (I beat the DS version so this better offer a lot of added content), Rayman (love the series but the mini-games = meh) and Monkey Ball (the Wii control looks silky smooth and precise in vids).
Elebits is a big wtf for me. After watching vids I have no idea if it will be worth it.
I'll score Slug Anthology too, if only to play 6, but I want to focus on games that use the Wii controller at launch.

