The Settings.settings under Properties in a C# project is a nifty feature that will let you save and load settings that are persistent as they are automatically saved in a hidden appdata folder by the .NET framework when you call the .Save() method. Use user-scoped setting for being able to change your settings during runtime (it's the default setting in VS2010).

Saving:

Properties.Settings.Default.Foo = "foo";
Properties.Settings.Default.Save();

This lets you avoid the registry more and manual file handling for saving and loading runtime configuration.