How to take a screenshot on Windows 7 and auto create screenshot file on desktop like Mac?

I use Screenpresso. It's free, portable and only uses the Print key (with modifiers).

Download NirCmd, AutoHotKey and Install them both. (Copy nircmd files to either Windows directory or extract it to a new folder).

Change this to relevant directories where the nircmd executable is stored and the path to your desktop.

c:\path\to\nircmd.exe savescreenshot c:\path\to\desktop\Screenshot.png

If everything goes fine, you should see a screenshot on your desktop. Now to make PrintScreen to execute that command. This is where AutoHotKey comes in.

I just modified the Script found here. Create a new ".ahk" file using Notepad, Paste this and modify as needed.

#NoEnv
SendMode Input
SetWorkingDir, path:\to\desktop

PRINTSCREEN::Run, c:\path\to\nircmd.exe savescreenshot c:\path\to\desktop\Screenshot_%A_Now%.png
!PRINTSCREEN::Run, c:\path\to\nircmd.exe savescreenshotwin c:\path\to\desktop\Screenshot_%A_Now%.png
return

Now use the "Convert .ahk to .exe" tool which is installed along with AutoHotKey and create a executable.

Run that executable and press PrintScreen (and Alt+PrintScreen); See if that did the job.

Now just add a shortcut to that executable to your Startup folder (which automatically loads it whenever you boot).

Edit: Modified to add Alt+Printscreen and Timestamp to files.

Simply use the built in Snipping Tool. It will capture the screen and prompt you to save it to a .png file. If you want it to run when you hit PrintScrn then bind it to that key using AutoHotKey.