Well, seeing as I took a Gaelic class in university in the mid-90's and we used those books and tapes things as our textbook, and as I now remember all of ONE word of Gaelic, I will have to say... no.
It'll probably get you STARTED, and get you to learn the basics, ("yes", "no", "où est la bibliothèque?"), but if you actually want to seriously be able to speak the language, I would suggest taking an actual class and/or making a friend who speaks that language.
Yes. I think to really learn a language you must be in an environment where you are forced to speak the language, without a dictionary. Best way to learn a language is not by translating it into your own but by learning it from others through body language and pointing to objects asking what they're called.
You should check out the Pimsleur Language Lessons. I've seen all types of different language packs in various places on the net. I'm sure if you look hard enough, you can find them (I've found a bunch on Kazaa and at www.suprnova.org).
I've been listening to the Mandarin Chinese Lessons, and I think it's a very good way to learn a new language on your own. Check them out.