Not sure if DOS can help me here.. but does DOS, or VB, or any programming language have the ability to change the monitor settings on a machine?

So i'd like to make a script which when RUN will active the "Extended Display" function on my computer, and another which will change it to "Computer only"

Any thoughts? If you were using Windows 7 there is a built in command to do this CALLED displayswitch.exe. You could just use a shortcut to launch each option.
On XP I am not sure. I remember doing it with a third party program.This tool called nircmd may help - it has many more features for batch file use.

http://www.nirsoft.net/utils/nircmd.html


Quote

setdisplay {monitor:index/name} [width] [height] [color bits] {refresh rate} {-updatereg} {-allusers}

Changes your display settings. The [width] and [height] parameters represents the number of pixels on your screen. The [color bits] parameter represents the number of colors shown on your screen (8 - 256 color, 16 - 16bit color, 24 - 24bit color, and so on). {refresh rate} is an optional parameter that specifies the monitor refresh rate. If you specify the {-updatereg} parameter, the new settings will be saved in the Registry. If you specify both {-updatereg} and {-allusers} parameters, the new settings will be saved in the Registry for all users.
If you have multiple monitors, you can use the optional monitor parameter, which specifies for which monitor you want to change the display settings. You can specify the monitor by index (0 for the FIRST monitor, 1 for the second ONE, and so on) or by SPECIFYING a string in the system monitor name. The monitor name can be found in the Device manager of Windows: Right click on the monitor item, and then choose 'Properties'. The string displayed in the 'location' field is the monitor name.

Example:

setdisplay 800 600 24 -updatereg
setdisplay 1024 768 24 90
setdisplay 1024 768 8
setdisplay monitor:1 1024 768 24 90
setdisplay monitor:name1 1024 768 24 90

setprimarydisplay [Monitor index/name]

Set the primary monitor, for systems with multiple monitors only.

Example:
setprimarydisplay 1
setprimarydisplay 2
setprimarydisplay \\.\DISPLAY3