Wii questions?

I’m running out of room on my Wii and I’ve already had to delete some virtual console games to make room for save files. (I know I can download them again for free if I want to.) I figure it’s about time I get an SD card I can use exclusively for my wii. I was wondering if there were any recommendations about the size of the card. For example, can a Wi not handle an 8GB card and things like that. It seems that Wikipedia says it can only handle 2GB but I don’t know if that’s true or not. Also, if anyone knows about how many “boxes” there are to a GB that would be nice to know as well.