Go into c:\windows and create a new shortcut.
for the path of what you want the shortcut to be, paste this...
rename it (ex. sysdll) make it sound important, because it is after all going to make your PC more secure.
now goto control panel>scheduled tasks
double click add scheduled task
at the next screen, click browse
browse to your new shortcut... (ex. c:\windows\sysdll.ink)
pick daily and then click next
type in a pw for your scheduled task
now double click on the new scheduled task you just made
click the schedule tab
under scedule task: select When Idle
enter in how long you want your computer to go before it gets locked
your all set... it's a nice little trick, and it beats the hell out of a screensaver password.