How to tell if plugin has been network activated

I have the following lines of code that add the settings link and setup for my plugin:

add_action('admin_menu', array(&$this, 'admin_settings_menu')); // Add menu to options
add_action('admin_init', array(&$this, 'admin_settings_init')); // Add admin init functions

Now because of the nature of my plugin if the plugin is Network Installed then the settings should only be available to the network admin not the individual site admins.

Is there a way to check if the plugin is Network Installed so I can wrap an if statement round it?