how to apply a function to a KEY

Hi Everyone.
How can I apply a Function to a certain key?
For example, When I press F9 I want to show the Desktop (in spite of clicking on the icon in QuickLauch panel)
Answer #1
just press
WIN+D
its much faster
Answer #2
:O ohh brilliant.
u made my day.
I was searching on the internet how to change this, and there’s a method, but i’ve to build a new registry key, and for me its odd.
Cheers again.