Redirecting old articles to new articles

[twistsol]

I asked this on vBulletin.com a few weeks ago and received no response so I thought I'd try here.

Problem:
In our old vb3 installation, we had a directory for articles from pre CMS days. This articles directory was in our forum root. In some cases there were .PDF files in /articles/files and in other cases, a single directory was dedicated to an article for example a review of the Ryobi BD4600 sander had an html file and other supporting files in /articles/bd4600.

When we upgraded to vb4, I manually converted all of these old articles into actual CMS articles and we were able to leave the old articles directory in place. We are now on vb 5.2.3, and the articles system won't work with that directory on the server so it was removed as part of the upgrade. We now have over 4500 not found search engine crawl errors most of which relate these old articles. If you try to navigate to one of the old articles you receive the appropriate error message below.

Invalid Page URL. If this is an error and the page should exist, please contact the system administrator and tell them how you got this message.

The actual Question:
Is there a way that I can redirect these old links to the actual VB5 article through .htaccess or another method?

On our site, I'm willing to update all the bad links manually, but there are many other external links to these same articles.