Jarvik7 wrote:
Something to watch out for with the Sonomama jiten: It's not an instant-on dictionary, which will dissuade you from using it, and it's physically impossible to look stuff up while you're playing a (Japanese) game in your ds.
Well a Canon wordtank can't play Zelda now can it? 
For what it's worth, Sonomama Jiten is absolute great. I found it pretty helpful with studying, though I admit, I'd rather have a Canon or Casio wordtank, but right now I can't afford it and Sonomama Jiten fills that position nicely till I get one of those wordtanks. Using my DS as an e-dictionary beats any looking up in an actual dictionary or turning on my computer to look up that one word. 