Newbie learnin' Japanese using a book?

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Might seem like a bit of an r-tarded question. But up until now I've used audio tapes to learn Japanese. Basically, progress had been pretty slow. I wanted to learn quicker so now I'm using a book. However, I'm confused about what I should be focused on learning to start with:
The first lesson is covering words/characters. Like Nouns, particles and their uses etc. But there are a few conversations. I was wondering if I should focus on learning the basics of the language for now. Or if I should be trying to learn the entirety of the conversation/s too.
I decided that rather than trying to decide this myself, I would consult the oh-so wise and friendly Yahoo! community.
Thanks.