Colin on Ubuntu’s still-not-working-properly dual head support.
My own experience with a single display when trying to connect a desktop PC (also using the GM945) to a 1920×1080 screen was very poor: XP just worked (perfect display and resolution detection), and Ubuntu didn’t – all I got was 800×600, and no amount of finagling helped.
Until it’s at least as good as XP in this regard (I mean, I’m not even trying dual head yet) Linux is not an option for me.