I have inherited a Drupal site on which (for some reason) there are two different content types for news: one for press releases and one for everything else. I would like to combine the two and use a taxonomy to categorize the press releases and other news types.
Is it even possible to do this? The site is using a number of modules, including Views and CCK, and I don't know how much a change like this would affect module data.
http://drupal.org/project/node_convert
The module linked above works extremely well for migrating nodes from one content type to another.
When you are done, you can then use VBO (http://drupal.org/project/views_bulk_operations) to mass manipulate the taxonomy changes you need.