The Server option is available on the Choose an installation option page in Microsoft Dynamics NAV 2009 Setup.
The single component in the Server option is the Microsoft Dynamics NAV Server, which constitutes the middle tier in the Microsoft Dynamics NAV three-tier. (The RoleTailored client is tier one, and the Database Components, along with SQL Server or SQL Server Express, is tier three.)
Installing Microsoft Dynamics NAV Server on encrypted drives is not supported. You may run into issues if the server runs as a user that does not have access rights to the encrypted files.
When you choose the Server option, Microsoft Dynamics NAV Setup installs the following component: