Purrint is another way to automatically save image files in Windows after pressing the PRTSC button. It's available for download here. [If you have the AutoHotKey executable running which was discussed in last night's tip, close it. It will stop Purrint from running.] It will give you the option to either copy a screen to the clipboard, print it as a hard copy, or save it as a file.
If you click on Options (then click on the cat to bring up the advanced options) you'll see you can set Purrint to automatically save files to a particular location, without it actually appearing. You can access the Purrint interface again by clicking on its icon in the system tray.
It's also possible to use Purrint to automatically save images at a set time interval.