My boss Neil just published a post on "Application Considerations When Upgrading to Windows Server 2008." Very nice and complete article. This should be your first read if you are in the process of evaluating Windows Server 2008. Content:

  • Changes When Upgrading to Windows Server 2008
  • Upgrade Process
  • Application Compatibility Checks
  • Changes that May Impact Your Applications
  • The Quarantine Directory
  • Folder Hierarchy and Names
  • Unsigned Software in x64

I suggest paying extra attention to the upgrade process.

"Instead of just installing new versions of binaries over those of an existing computer, the new operating system is installed side-by-side with the older operating system. Then the data and settings are migrated from the older version to the newer version, and then the source is deleted."