Minimum Tables to Export/Import for Upgrade/Transfer

Hi all. Is there a list of the minimum tables required to Export/Import when upgrading?
Am upgrading from v1.3.8a to v1.5.6c. and want to keep it as clean and "new" as possible for a completely new look and operational stability, so really, I consider it a new install. But I want to retain my Admin, Categories, Products, Customers and Orders (and anything else considered "historically important"), but not any current layout, default page content or other stylistic changes.
Have read through the How To Rebuild page which assumes a full export/import.
Is there a list of what to export (or more likely what NOT to export) that will keep my current sales intact? Or am I looking at a table-by-table comparison between a clean install and a full export/import?
Thanks.

Personally, I think you're looking for trouble trying to merge the old/new databases. I suggest that you take your existing database and let the zc_install process do its thing.

After the database upgrade, you can strip any no-longer-used tables and/or fields.

Thanks lat9. Was having trouble to get an "Update" button to show up to update the current database - just the "Install" one that would overwrite everything and was getting frustrated.