Um Tony, why don't you just use the old 3 fingered salute (Ctrl-Alt-Delete) and then hit "Enter" to lock the workstation? Is probably even faster than starting your program from the system tray and the screen saver will come on all by itself after the time you have set for it. Don't need a password on the screen saver.

(list 6284, Mk1 S/N 00299 4GB blue [for sale]. Mk2 S/N 080000094 6GB blue)