SIMTel Page on scrnmode.zip
The above page links to a free, open-source program that can change your resolution from the command line. The page says it's only for Win9x/ME, but it works fine on XP (that's where I use it). Just create a startup script for the users that uses this program to change their resolution. You probably have to set one up for yourself, so the resolution goes back to 1024x768 (or whatever you like).
Hope that helps.