Well I speak French fluently already, so I never downloaded any "Lean French" software or materials.
But as for language learning in general, I've used the Rosetta Stone, its quite good actually, especially to pick up vocabulary quickly. Its quite expensive if you buy it... but I've seen a few ISO's floating around on torrent sites.
As for which program to use, it really depends on what your goal is. If all you need is to learn phrases to have basic conversations, such as while traveling, you will probably find many free sites that you can get that info from, and I am sure there are some free (not necessarily warez) programs for that too.
It will help you a lot with the vocabulary, without getting bogged down in details like verb tenses, complex sentence structures, etc. Building up your vocabulary words is the most important step, for example, if you go to a restaurant and say "Hamburger, please", people will understand... but if you just say "Euh.... Hello...Sir, I...want"... you wont get anything!
If your goals are to be more proficient in French, then the best way to improve is to practice speaking in French with others, read the newspaper, watch shows in French, etc.
Hope this helps.
