My local library makes Rosetta Stone available for download and use at your home computer via Flash. You just sign in at the library website. Maybe your library has something similar.
French is definitely one of the easiest languages for Americans to learn. In order not to sound like a twerp when you speak it, you'll need to learn to pronounce things the French way. Gotta open your mind a little. As to how hard it will be for you, there's no way to know. It will definitely take some serious and sustained effort if you want to get into literature. Some of the best learning tricks are flash cards, watching moves and news in French with English subtitles and vice versa, reading children's books in French, and practicing conversation or e-mail with someone else who wants to learn English.
If you find French doesn't interest you as much as you thought it would, do consider trying another language. It will broaden your mind, improve your grammar, open up opportunities, and give you confidence. Consider which cultures interest you, because those are the cultures you'll have to study and immerse yourself into in order to get really good at a language.