Pressing Windows M might be an alternative although it does not minimize all open windows. It was for instance not able to minimize XMPlay, my music player. Fortunately it is not complicated to recreate the Show Desktop shortcut.

Create a new text document and add the following lines of code to it:

[Shell]
Command=2
IconFile=explorer.exe,3
[Taskbar]
Command=ToggleDesktop

Save it as “Show Desktop.scf”. Double-click the file to check if it is indeed minimizing all windows. You should at least have one window open to see the effect.

Right-click your task bar and uncheck the Lock The Taskbar entry. Now drag and drop the Show Desktop.scf file to your quick launch bar. Once that is done right-click the task bar again and lock the taskbar again.