To answer your question, I don't know of any software that can teach you Japanese, but if you can get a hold of the Pimsleur tapes/CDs you'll be off to a good start learning how to speak Japanese... learning how to read/write is another thing though.
I studies Japanese for 3 years when I was younger, some people joked about it, claiming the language sounds funny. In the end I wasnt learning anything new so I stopped going to lessons.