Creating Show Desktop Script For Keyboard HotKey

I've just got a Logitech Cordless Desktop EX110, and the keyboard (like most moderately priced keyboards) has numerous 'hot-keys' (like music controls, email button, internet button, calc button etc.) On the side of my keyboard is two hot keys, a 'back' button and a 'close window' button. Now in the Logitech SetPoint software it is possible to customize this buttons function. So I want to make it a 'show desktop' button.

Here's the problem, the SetPoint software is a bit restricted and gives me these (function) choices: Default Task (in this case, close window) Open Web Page Launch Program Open File Open Folder Show Custom Menu Keystroke Assignment Do Nothing So, first of all i tried Keystroke Assignment. Well that would work, just there is only one keyboard short cut i know to show desktop (windows key & D). But this program only takes short cuts that use alpha-numeric keys, Alt or CTRL keys (or in comination, like CTRL+ALT+R) - not the windows key.

Are there any other keyboard shortcuts to show the desktop? Can I make a new keyboard shortcut? But before I started asking that question i thought well ill try 'Open Program'. Found on the Microsoft website the script for Show Dekstop.scf, got that all ready. Targeted the file in SetPoint, no it doesn't work - SetPoint's 'Open Program' only works with executable (exe). So I tried, open file - with the same file, nope - the computer does nothing when that happens.

So let me summarise: Is there an alternative shortcut to Win+D? If not, is there a way of me making a new shortcut (side note, without using a third party program like HotKeyz - coz it doesn't work that way either). Is there an executable script that will show desktop. And I'd need it to be a background sort of script, it'd be crude if everytime I pressed the button up came the cmd box.