Hello Brian ,
Try this
To install unmanaged Symantec Endpoint Protection 64-bit client software on 64-bit Windows Server 2008 Server Core
1 Insert the product disc into the drive.
2 Change directories to the root directory of the product disc.
3 Type cd SEPWIN64\X64, and then press Enter.
4 Type vcredist_x64.exe, and press Enter.
5 Change directories to the root directory of the product disc.
6 Type Setup.exe, and press Enter
7 Follow the steps of the installation wizard to complete the installation.
To install unmanaged Symantec Endpoint Protection client software on Windows Server 2008 Server Core (all other clients)
1 Insert the product disc in the drive.
2 Open a command prompt.
3 Change directories to the root directory of the product disc.
4 Type Setup.exe, and then press Enter
5 Follow the steps of the installation wizard to complete the installation
https://www-secure.symantec.com/connect/forums/sep-client-windows-2008-r2-core-edition#comment-4346671