Network Manager is automatically installed with the GNOME Window Manager. It is especially useful in a laptop environment. For servers, the interfaces file is probably the best and most flexible option. Of course, ifyou require certain features available only in one or the other, use whatever provides them, combining the two techniques if necessary.
Don't attempt to control the same interface using both methods. While Network Manager will refuse to manage a connection defined in the interfaces file, and the ifup command will generate an error if it attempts to set up an interface already controlled by Network Manager, it is possible to circumvent these protections.
