I had the same idea, I love the thought of the pop-up coming and saying that I have mined a block, but unfortunately it is near impossible.
I turned on the mining in Bitcoin-qt on my crappy old PC, left it for a few hours, then got sick of my PC running even more slowly than normal, so turned it off!

I doubt you have the patience to really give it a go, and if you do, you will still find nothing! so I guess I wouldn't recommend it!