CMS Integrating new CMS with existing pages
 

Situation: well-established personal finance site has hundreds of static html pages maintained with web publishing software (no cms) and a moderately active message board that is being converted to vb. It doesn't currently have a blog, although the front page looks more or less like a blog without user comments. Most of our traffic comes directly to internal html pages rather than the home page or the message board, mainly due to search engine rankings but also because of incoming links.

I'm looking for comments on how best to implement cms in this situation. Initially I assume we can use cms for new pages while leaving the old ones in place. Ultimately we'd want to migrate everything to cms, but without losing all the traffic that lands on the existing html pages. I assume we'd need an htaccess entry for each page we converted. Not sure if this really preserves the traffic, as the search engine may take a different view of the converted page. What's the best strategy here?