Demo One
In this demo you can see that when you click on the button in the form below it will become disables until the form has posted. Try the form below.
But as you can see from the form below, if the form doesn't post for some reason, the user is now stuck. Also, if I am using ASP.NET with multiple buttons in one form, this has compatability issues.
So, lets try something other than disabling the buttons.