You will need the Windows SDK installed. There is a function called ChangeDisplaySettings in the Win SDK that will do this. You can get a DEVMODE enum for the current display setting with EnumDisplaySettings and make changes to it. The code would look something like this:
DEVMODE DevMode;
EnumDisplaySettings(NULL, ENUM_CURRENT_SETTINGS, &DevMode);
DevMode.dmPelsWidth = 1024;
DevMode.dmPelsHeight = 768;
ChangeDisplaySettings(&DevMode, 0);
Best Regards,
Chris Matthews
National Instruments