One last thing.. Google is looking for freshness these days. So you might want to write new articles about the same things but with an updated feel?
For our main site (which has quite a few articles dating back to the late 1990s), long-established pages often rank much high in Google than newer pages on similar topics do--even when the newer pages are a better fit for given search queries.
On the other hand, Google seems to be much slower to index and rank newer articles or pages these days--at least on traditional Web sites. Our blog posts--which are on a separate domain--are indexed and ranked quickly, but our non-blog articles seem to get stuck at the end of a queue. Maybe Google's idea of "freshness" is "recent posts on a blog."