Is there a function call to detect the Ctrl- Alt- Del keys are being pressed both in NT and 95/98?

I want to disable the Ctrl-Alt_Del in win95 when my screen saver program lock the PC? How can i do that?

In NT, although the Ctrl-Alt-Del keys are handled by winlogon, when a logon dialog box appeared, it will
dissapear again if the user pressed the Ctrl-Alt-Del keys, how shall i solve this? I should detect the key
combinations is being pressed and then send a WLX_SAS_ACTION_NONE to winlogon right? So how
to detect the keys are being pressed??