The topic of how to build a site comes up often here and many times members including yours truly suggest WordPress, but we (or at least I) am normally referring to setting up a WP blog. I know WP can be used as a full content management system and today ProBlogger has a short, concise article about using WP as a complete site building solution.
Beyond a Blog - Running a Full Website Using WordPress
"Some businesses start blogging to expand their website. Some start with a blog. For the strongest online presence, business websites need both static content and dynamic news, a.k.a a blog. The blog builds traffic and establishes authority. The static pages helps convert that interest into business...
WordPress has everything you’ll need to build a complete website, without installing any plugins or changing anything. In fact, it’s already the most popular content management system being used today…"