My wife, Marcia and I have recently discovered DuoLingo. We both love it. I agree with Edd, Rosetta Stone didn’t do anything for me.
DuoLingo is fun to use and because of that quality, like Susan said, it helps you to stick with it. I am currently on a 45 day streak.
Here is the link: http://www.duolingo.com/ and it’s free!