Jquicktrans is a wonderful Japanese dictionary and study aid program for Windows. It's also cheap at only US$10 (one of my favorite features ). I've never actually used the study aid part of the program, so I can't comment on that. But I love the dictionary. I espeically like the search flexibility. You can use a ? to match any single character and * to many any number of any character. For example, doing a search with 食? will give you all the results that start with 食 and are followed by exactly 1 character. Doing a search with 食* will give you all the words that start with 食.