If you want to take timely screenshots of your current screen then AutoScreenShot is a free program which lets you to do this in a simple and easy way, just install this program. Another advantage of this application is that it does not have any active window, so you can use this application in stealth mode to capture screenshots of the current screen at timed interval you had specified.
It will keep taking the screenshots of the screen timely and will save them in the defined directory without the user getting to know about it, it does not even display a system tray icon so that no one could come to know about this program running unless they see its process running and showing up in task manager.
It allows to compress the screenshots, by default it takes the screenshot in jpg format, you can also specify the time interval in between two snapshots and number of recent snapshots to keep, rest old snapshots it will delete automatically. In all this seems to be a nice utlity, which does what it says without using much memory and CPU so we have our thumbs up for this application.
It runs on windows version released till now including windows 7, we have just tested the utility on our windows 7 32 bit Ultimate Edition, the only problem we faced it that after running the program we were not able to access the program settings back.