OSX server has a built-in VNC server (as do OSX workstations). This works fine with viewers like UltraVNC which is what I use to connect to a OSX workstation on my network.
If your provider is going to perform initial configuration of the server for you, be sure to confirm with them that you want VNC turned on and have them set a password. If you will have access to the machine for initial configuration, you can turn on the VNC server in System Preferences > Sharing and enable Screen Sharing. Then the Computer Settings button will let you set a password.