Jonathan:
To be quite honest, there are not any precautions that come to mind, except for one - verify you have a valid SQL Server backup of the sgvault database before deleting data or formatting a drive.
After you've finished installing the OS, you will need to install the required components for Vault
- IIS
- .Net Framework w/ ASP.Net
- SQL Server 2000 w/ any service packs
Once done with those steps, you can restore the sgvault database within SQL Server.
Finally, just re-install the Vault Server. Let the server installation know the server's name. It should find the sgvault database, do not over-write this database. After that, the installation should take over from there.
HTH