I agree with Vincent that storing your data in files might not be a bad thing ... but "to database or not to database" in a philosophical sense probably isn't the most important question. I'd start with some practical points and work toward the database vs. flat-file issue:
- What's your business model?
You probably need to be looking at aggressive partnering and syndication. That leads to a need for multiple concurrent versions of your content (in terms of presentation). It might be more convenient to build that dynamically out of a database.
- How do people find your content on your site?
There are two basic modes of navigation: browsing and searching.
Effective browsing requires an information space that makes sense to the customer. If you change your mind about how to structure that space -- or, if through syndication or partnering you need to support multiple alternative structures -- how does your backend support that?
For searching, how good are your search tools? (Not very good right now; try searching for "sheet rock" and look at the odd and duplicate hits.) If your content lends itself to structured searching, flat files won't do. Think about applying key words (not full text, but KEY words) to the documents to relate them to one another. A database might be the best tool for that.
- How often does your content need to be updated, expired, et cetera? Maybe not a problem for you; sites with heavy updating or need for automatic expiration (with automatic management of links to an item) absolutely should be building on a database platform. That might or might not mean run-time dynamic pages; it could be done by "printing to html" from a database-backed content-management system.