For this project to be really interesting and show cool results, you may need to analyze largish samples of each person's texts, and then see if you can use those results to answer a question like "Is this new unknown text written by this author?" Luckily, there are places where you can get entire books by specific people:http://www.gutenberg.org/http://archive.org/
That way you will be highly likely to answer the questions "how can you determine the person from their writing style?" or "is it possible to determine the person from their writing style?"
BTW, I think "is it possible to determine the person from their writing style?" is the better phrased question of the two, and I would bet money that you will discover that it is indeed possible.