How to determine inactivity?

I would like to determine that the user has not used the program for a certain time frame and shut it down (kinda of like a screensaver displays at a certain standby interval).

Any ideas?

You can have a timer that is always running, and when the
user do something, reset your timer. And if your
Timer get to a cetain amount of time well -->THE END!

How long , or better question, what the maximum time that can be set by a timer? How much of a memory hog would this potentially be leaving it running all the time?

Is there a way to do this with API since the time is limited to a minute max?

Use the GetTickCount api