OK, this is the rub. If you set the Screen Resolution to high, it won't work. I have a 19" 4:3 monitor. Screen resolution is 1280x1024. When I first hooked this monitor to my box, it adjusted itself to that resolution. When my buddy brought his box over (to use my faster connection) he didn't bring his monitor. Hooked my monitor up and no go. His box was set for a much higher resolution than my monitor would handle.
But since you're connecting to a new box, Windows should adjust the resolution so that it works.