I was trying to upgrade the site, botched it, and my web host deleted the backup, so we're working with a file system restore from last sunday. The database is in tact, so no new posts or blog entries should be affected. There may be some images or uploaded files that're gone, but we'll see what more I can piece together.
I'm going to try a different approach with the upgrade and setup a new drupal5 installation and import the database in to the new one, rather than going the upgrade route.
This shouldn't result in more site downtime, but please bear with me with any additional inconsistencies the site may experience.