Often, new faculty wonder if they should try to publish a book or try to publish articles. What should one do? First, the most important consideration is the convention in your field. While norms in your department should also be strongly considered, sometimes faculty composition changes over time, so the norms in your field are key.
That said, all things being equal, go with the articles, especially early on. Why? Articles average 20 pages in length, while a book is usually 200-400 pages. Perhaps this is an overly simplistic way of thinking about it, but if you can write five articles and send them to journals in the same amount of time that you write a book, you odds of getting some of those articles published far out way the publication of your book. And, in most fields, five articles in solid peer-reviewed journals "count" more than a book in nearly all circumstances.
In some fields, one article in a good journal actually counts more than a whole book. This is not true for the humanities, where books are valued a great deal. Still, putting your eggs in one basket with a book can be a very risky proposition.