Configuring Screen Resolution from group policy in windows 2003 Server

There are two parts to this answer, the first part explains why you don't want to do this, the second part show how you could accomplish what you are trying to.

Part 1:
For very good reasons this group policy doesn't exist (see above)  I'm also pretty sure that Windows is programmed to be able to modify resolutions whenever it wants to (if it detects a problem)  The group policy works, if windows wants to do something group policy says not to- that just quits working and if this were the display it would mean the computer.  The current settings for the display are in the registry for boot up at hkey_users/.default/control panel/desktop The screen resolution isn't in these settings (group policy is simply a script for setting values in the registry)  The screen resolutions are set for the user on the display device.  So even if you were insane enough to want to try you would have to write a group plicy entry into an .adm file (these scripts are found at c:\windows\inf and end with .adm take a look at them if you want to) Basically they tell group policy what registry settings are avilable and then it build the policy.  I have an Nvidia card and my screen resolution is at
HKLM\Software\Microsoft\Windows\CurrentVersion\Control Panel\Settings\Video\PCI:VEN_10DE&DEV_0322&SUBSYS_12801682&REV_A1\Monitor:Default_Monitor:{4D36E96E-E325-11CE-BFC1-08002BE10318}:0000,0\1152x864 x 60Hz\32 bpp Where PCI:VEN_10DE&DEV_0322&SUBSYS_12801682&REV_A1\Monitor is my graphics card and Default_Monitor:{4D36E96E-E325-11CE-BFC1-08002BE10318} is the monitor. So this registry value would need to be set with the correct value.  

What I'm saying is that the huge numbers that look like product id's identify the devices and the registry settings and they are unique for each graphics card.. Windows sets these settings when you choose a resolution so they can't be dictated by group policy, unless you want to find out the identifiers for every type of graphic card you have and then create adm entries and then set them for each and every type of card (YOU DON'T WANT TO DO THIS.. I'M JUST SHOWING YOU HOW INSANE AND MORE TIME CONSUMING IT WOULD BE TO DO IT THIS WAY.)  Microsoft has made it this way by design.

Part 2: If you really want to do this, read on...
You're going to have to find a program that sets the resolution and then deploy it to the machines.  I would recommend using visual basic (I'm not going to put code here to do that as it goes beyound the scope of this question)  Here are links to articles with sample code that could be used.. http://www.google.com/search?hl=en&q=set+screen+resolution+visual+basic  After you have created an exe file you can then deploy it in a start up script or another of simple ways.. I usually write a batch file that would copy it to each computers c:\documents and settings\all users\start menu\programs\startup folder.  This would have the effect of running your exe file each time a user logged in.  You could also take the extra step above and disable the tab in display settings using group policy and then users would effectively be locked into that resolution.  Hope this answers your question.