I'm familiar with the Rosetta Stone software. I checked it out from the local library, though lacked the motivation to use it more than a few times. It seemed user friendly.
Everyone always told me the best way to learn a language was to sleep with the dictionary. So married a French man and we speak English at home, go figure.
If you have the time and resources, really immersing yourself in the language and culture is most beneficial. I took classes at both Alliance Francaise and the Sorbonne, both good programs, and offer my opinion on them here...
Paris Schools of Language � La Sorbonne vs. Alliance Fran�aise I like to pick up new vocabulary by watching movies either in French with English subtitles or preferably English with French subtitles but always in the original tongue.