Since windows XP we are using Logon screen to lock our desktop (our separate account) but using windows 7 you can lock your desktop, transparently that means you don’t need to logoff or leave your system at switch user more to lock its desktop. You just need to run ClearLock, using it you can view what’s going behind on your screen even if your desktop screen is locked.
ClearLock is a transparent screen locker aimed to make the computer tech/system admin’s lives easier by providing a way to disable input to a computer while still allowing you to see what is going on. You just need to download and run by yourself to see how it works.
ClearLock is not at all a security system. The main purpose of the application is to keep meddling users from screwing with your computer when you are fixing it. Remember it will not keep your computer/data safe from someone who is determined to get at it.