Have not done that, I'm assuming you would need an App on you machine that can Mirror your entire Desktop to the Cast Receiver.
I haven't tried this, but I'm going to go hunt down a Chromecast now and give it a shot since we've got a bunch of TVs I think I could use this with:
Such a great idea. Why is it that I'm using two Monitors when I could just use a 60" 4k tv?
Wish I thought of that first.
I just tried this with my HD ready spare TV and Chromecast (with lowered 1280x720 resolution from my laptop)... the image (or video) quality is OK, but there is too much "latency" for this to be used as a number one display. For showing models it's not smooth, but for patient presenter it is OK (everything comes ½ second late)
I used this method:
Mirror Anything from Your Computer to Your TV Using Google Chromecast