Rosetta stone is good software but takes along time to learn with it because it teaches a lot of nouns and verbs first - that dont have a lot of application in "active vocabulary"
its working very well for my daughters hindi lessons (as she is only 3)
for our learning spanish i tried so many programs and CD's- including pimsleur but they all bored me to tears until i got hold of
MICHEL THOMAS's CDs :
http://www.michelthomas.com/
after doing just the first 6 lessons (just a couple of hours) i could converese wth friends in south america on IM quite easily. This is because he teaches you in a way that you do not force yourself to "remember" anything - and also he explains the language - its not like a parrot school just repeating - you actually learn to THINK about how you will translate your sentance.
Very practical and i think its the best