Sorry I can't offer any input about Rosetta Stone, but I really wanted to get into the conversation.

I too am on a mission to learn a language. I grew up with my Mom speaking Dutch to me and in return I would answer in English. So, I understand it almost fluently as far as a day to day conversation goes. I wouldn't be able to jump into a business conversation or a history class. I can speak Dutch a little too; however, I have a very hard time forming sentences and remembering the words when I need them. It is the grammar that I am missing. What has worked well for me in learning Dutch is going to Google.nl and searching for "learning Dutch" in Dutch. I found some really great free sites that I would not have found by using our Google. Of course it helps that I know a little Dutch.

We traveled to the Netherlands, Belgium, and France in 2008 and I was so impressed by how many people there could speak so many languages. It makes me really want to hold a conversation in Dutch with my Mom sometime in her lifetime.