we need some way of installing the bare minimum to our automated builds.
That means we need support for installing just enough to run msbuild (no need for emulator, VS Express, XNA etc.). Down the road, the emulator might be handy for running automated unit tests as well.
There is a hack described here to enable this scenario: http://blogs.msdn.com/astebner/archive/2010/05/02/10005980.aspx, but we need official support for building the software in an automated fashion on Windows Server