DVD Language programs

Almost once a week, I get a question from someone about whether s/he should invest in one of those pricey language-learning DVD programs, like Rosetta Stone. To me, those language learning disk things are a waste of time. I frequently tell people that learning a language is like learning ballroom dancing--you need another living, breathing human being to interact with.
But I still get questions from folks who plan to travel, say, to Italy or Mexico--how can they learn a few polite phrases before their trip?
Students sometimes ask if buying one of those language programs would help them in their classroom study of the language.
My basic answer to both of those questions is--if you enjoy using it and continue using it, it might do you some good.

Until very recently, most of the Armed Services used either Rosetta Stone or something related to it, in helping service members develop their language skills. The Air University Culture and Language Center at Maxwell AFB has recently stopped using them for ab initio (from the start) language learning. In other words, it's been their experience that trying to learn a language from scratch using Rosetta Stone is not very useful. Someone that already has some knowledge of the target language can use the software programs like Rosetta Stone to maintain their skills, or to review, but it's a poor choice for learning the basics.
This was borne out recently in my own trip to Japan in 2009. I went there to visit my son who was stationed there--and I thought it would be cool to learn some Japanese before I went. I was really excited! I downloaded one inexpensive video program from download.com--and I purchased another MP3 program online. I loaded both of them into my laptop, hoping to have time to listen and repeat--I guess, during all that free time I have. And since I tend to be an auditory learner anyway, it seemed a good fit for me.
Suffice it to say that I went to Japan knowing--exactly as much Japanese as I knew before I purchased those programs. Almost nothing. In fact, I learned loads of Japanese while I was there--but almost nothing from the software.
So if you've just got to spend money on software or you won't feel you've had your daily vitamins, I say--go for it. But don't have too high an expectation about how much you'll really learn.