Sunnie: before you purchase a program, you may wish to take a look at some of the many free programs that are already offered, or some of the more cost efficient ones. There's several free programs specifically for learning the Arabic in the Qur'an (perhaps some folks who have tried several can recommend some over others, insha'Allah), for example.
http://www.madinaharabic.com/ is a free online program that goes VERY in-depth. For conversational Arabic I have been using
http://www.amazon.com/Ultimate-Arabi...688276&sr=8-50 I'm very happy with it, especially since it also includes regional dialects.
You'll find a lot of people on Muslim boards do speak Urdu, which is commonly spoken in Pakistan and parts of India. It's a beautiful language, and you'll find yourself picking up bits of it, especially as you start being able to read Arabic script.
IMHO I would not get Rosetta Stone. It is designed more for the traveler in mind and I have heard some people have a difficult time figuring out exactly what the program is asking for or providing, sometimes . . . for example, is the word provided supposed to be for "horse", which is the picture it might show, or is it "running", or "animal"? Research some other avenues first, would be my advice, especially since Rosetta is awfully expensive. :(