Add .xml to a Installer, without It being ReadOnly.

Question

I have a WPF (C#) project that has a Installer project. The thing is that one layer (UI) has a XML file that I wan't to be included in the Install.
That is to say, I wan't the file to appear in "C:\Program Files\appName\" when I Install the app on a client computer.

I have tried to change the "Build Action" but that doesn't work.
I have tried to include the file in the App folder in the "Primary Output..." in the installer, but then the file is readonly. (It has ReadOnly = False).

This is probably a easy task but I just can't figure out how to do it =/

Internet, thanks in advance.

ps: I'm working on a Win7 machine.