How to display defaultValues the first time a PreferenceActivity is started?

Question

I've defined my preferences in an xml file, preferences.xml. I've also got a SettingsWindow class which extends PreferenceActivity. I've set the android:defaultValue attribute on my preferences in the xml file but they don't appear the first time the app is launched. How do I load the default values defined in the xml file into the SettingsWindow the first time the activity is launched?