Right Click on your dock:
Settings --> View --> Show minimized windows.
But this trick activates an alternative animation for icons, that is slower than the default windows 7 one. And even setting it to "fastest" the animation is sometimes laggy, and i don't think it's an hardware issue.
I'm on an i7 (1,60 Ghz) 6 GB of RAM and a GeForce 230m.
Bye 