I'm trying to figure out the best way to get old blog posts to be recognized by a new build of blog engine.  I may convert the web 2.5 to a web application to take advantage of the precompilation.  I think my question would be applicable even if it were left as a website project.

The scenario - Lets say BE is on my server and I've accumulated 20-30 posts.  Then I want to pull BE down and push a new instance up with a theme I created or other visual changes via html/css.  I'm concerned the older posts wouldn't be recognized by the new instance.  The naming schema of the posts is really cryptic.   All of my posts will remain in XML format.

Can I add the names of the posts in an xml file with the new instance?  How should I deal with this scenario?

If your posts are in XML format (in the App_Data folder), they should all carry forward to the new version without needing to make any changes.  The same XML structure has been around for some time.

Here are some instructions on upgrading to BE 2.5.  The data in the App_Data folder does not need to be modified in any way.  It's good to keep a backup of the posts though just in case.