Shoutbox

you can do this with ultramon, install it then right click on the tray icon click shortcuts => create shortcut then it will come up with a wizard
select a random program to start (just use ping.exe)  then
hit next on the "Window Settings" screen and on the display settings screen tick "use custom settings" change the resolution and untick "Restore original display settings when application exists" then
hit next tick "launch this shortcut after logging in" and hit finish