Actually, it's for digitally signing Adobe Acrobat files.
We're using WinXP Workstation and Win2k Server. As a side note, we may just go with self-signing - Adobe doesn't work with any of the default certificate providers, and hence, the only way to validate a commercial certificate is to have a plug-in added by the issuing authority. This is a problem because we want people outside of our agency to be able to view our documents and verify their veracity without having to install anything beyond Acrobat.