How do I set the duration of "Log on to Windows" dialog box?

I’m looking to increase the length of time the Log On to Windows dialog box (where credentials are supplied) remains on screen before it reverts back to the ctrl-alt-del dialog box. Currently it appears to be set to two minutes on a couple of our windows 2003 terminal servers. I need to increase this as we’re introducing a new password management system which requires user input which will take longer than the two minutes so their sessions “time out” before they even log on. I’m hoping that increasing the length of time the log on to windows dialog box is available will get around this problem. Any ideas?