Software to monitor your computer while you are away from it?

Is there a good free program that will basically monitor your computer while you are away from it [something that you could maybe turn on/off]?

I don't like other people using my computer, and want to make sure that nobody in my house puts a keystroke recorder on it or stuff like that.

 

If it's XP or Vista, why not password your user login?

 

I believe any Windows can be Login password protected. I know 2k can. Am almost positive 95 and up can be as well. Has been a long time since I have played with ME\98\95. However it would be the simplest solution.

 

Password protect and also have it enabled when your screensaver activates. That way if you are away temporarily you will still be protected should your computer be running.

 

I was thinking about doing that, but I would prefer a program which does it instead. Something that maybe hides in the background or something while the computer is on.

 

I just use SSM with the UI disconnected to protect my system. This way anyone can use it without doing anything bad to it.