Is it possible to force the screensaver to appear whenever a computer becomes locked? Specifically on XP, 7 if possible.
I believe that the SS is only triggered when the timeout is reached, regardless if the PC is locked or not.
I do not believe that you can lock the machine and expect the SS to appear instantly, without a 3rd party program handling it for you.
There is an option to lock the PC when the SS is active, on XP and above, by selecting the 'Password Protect' tickbox.
Windows has several desktops. You're familiar with the one you are looking at right now. There's another one for the login screen. And there's one for the screen saver. Locking the workstation switches the desktop to the login screen. You cannot switch back to another desktop (like the screen saver one) until you login.
You can however get the screen saver started, that selects the screen saver desktop. Which automatically switches to the login desktop if you configure the screen saver that way.