http://www.bestbuy.com/site/WD+-+My+Passport+1TB+External+USB...
It's USB powered, meaning it doesn't have it's own AC power cable and is powered through whatever device it's plugged into. I know the Wii doesn't have powered USB's because I plugged my Kindle into it and the Kindle recognizes that it's plugged in but it won't charge.
I'm a PC player but I'll always have a spot for Nintendo. I grew up as a child as a hardcore Nintendo fanboy and I still love their games. The Legend of Zelda still gives me the magic feeling I had when I was a kid. :)