Re: Viewing photos on Wii
I've never paid much attention, as I've only looked at pictures on it when I first got it...and those were from my 3mp p&s of the time. Bear in mind that the Wii is a low-def source being viewed through a hi-def screen. Not a good combination. Think of it in the same way regular cable or network channels look after seeing them in high-def, they actually look better on a crt tv because the lo-def signal is getting displayed the same way. The hi-def amplifies the bad.
Re: Viewing photos on Wii
Like N8 said, Wii's are not HD. They run off an analog video signal and thus, your hi resolution pics will not appear hi res when viewed through the wii.
Pictures taken with the best camera in the world would appear just as pixlated, dont worry about it. Hook your DSLR's video out (probably a mini HDMI depending what you have) and view those on your TV and you'll see a drastic difference.