Okay, assumption is that you want your display to be permanently set to 1024x768 in "box format".
Your monitor must be set to use this format when receiving a certain profile (rez+refresh).
You can boot into W7, then use the monitor's on-screen controls to show what it is running at,
then try to re-create that in Vector.
Or, simpler: Use the same controls on the monitor to set the format as you want it.