They say the best time to learn a foreign langauge is when you're young, so why not try teaching your kindergartener as you homeschool? Actually, there are plenty of "immersion" programs for preschool and kindergarten kids to learn a language in a school environment, but there's no reason homeschoolers can't be just as successful.
Along those same lines, speaking the language with another person is much preferable over speaking it into a computer. Many of the available computer programs are excellent, but reciting vocabulary words to yourself or the computer just doesn’t give the same quality of feedback as if you were speaking them to another person.
If you or someone in your family isn’t a fluent speaker of the language you want to teach, and you can’t find a native speaker to tutor your kids either, the foreign language computer programs are your only real alternative, and while not ideal, they do get the job done. Check your local library also for language resources to help along the way, and above all, stick with it! Persistence is the key to learning another language, and starting young can only help.