My daughter's birthday is coming up in a little over a month, and I'm thinking about getting her a Nintendo DSi. The only question is, DSi or DSi XL? My younger brother has the XL, but it looks as though the only difference between it and the standard DSi is the size of the screen and quality of the speakers? Or is there more to it than that? I'd like this to be just a one-time purchase, since it's on the pricey side, so I want to make the *right* purchase! Help?