In a web application that I'm building, I'm going to need several disabled buttons. I already have the enabled buttons and I want to know what the best and easiest way of creating a disabled version of that button. For example, when a user clicks the login button, I want to disable the button to show that the click has been registered.
I have paint and paint .net and if I had no other option I could use a friend's photo-shop.
Here's an example of one of the buttons: 
Can someone tell me the quickest, easiest way to create a disabled greyscale version of a button like this?
