ASP.NET: Disabling a button control when clicked, and do postback

I'm not a fan of ASP.NET, but work is work, and I have to use it for now.
Beeing a fan of Open Source and PHP it's quite hard to get used to, but I find the structure of C# fun enough, what I don't really enjoy is the ASP.NET framework, seems too hard to do basic things, and too easy to do complex things (If you let it handle things for you).
Nevertheless, this is a common problem I think many people might have, when you have a button control which has a postback event associated, and you also want to associate some javascript to it, well, I saw many solutions but by far this was the cleanest and easiest.

Enjoy!